Programs & Examples On #Kermit

Kermit is a data transfer protocol, commonly used in the early days of the internet.

Why am I getting a "401 Unauthorized" error in Maven?

I got 401 error when used mvn gpg:sign-and-deploy-file command and the reason was that

//<maven_home>/conf/settings.xml
//To get `<maven_home>` run `mvn --version`
//for example

/usr/local/Cellar/maven/3.6.3_1/libexec/conf/settings.xml

does not include <server></server> tag body that you can get via

LogIn to Sonatype -> Profile -> User Token -> Access User Token
//https://oss.sonatype.org/#profile;User%20Token

//it will generate something like
<server>
  <id>${server}</id>
  <username>{name}</username>
  <password>{pass}</password>
</server>

//where `${server}` is the same as `-DrepositoryId` parameter in `mvn gpg:sign-and-deploy-file` command

Keyboard shortcut to comment lines in Sublime Text 3

I prefer pressing Ctrl + / to (un)comment the current line. Plus, I want the cursor to move down one line, thus this way I can (un)comment several lines easily. If you install the "Chain of Command" plugin, you can combine these two operations:

[
    { 
        "keys": ["ctrl+keypad_divide"], 
        "command": "chain",
        "args": {
            "commands": [
                ["toggle_comment", { "block": false }],
                ["move", {"by": "lines", "forward": true}]
            ]
        }
    }
]

How to unpack and pack pkg file?

You might want to look into my fork of pbzx here: https://github.com/NiklasRosenstein/pbzx

It allows you to stream pbzx files that are not wrapped in a XAR archive. I've experienced this with recent XCode Command-Line Tools Disk Images (eg. 10.12 XCode 8).

pbzx -n Payload | cpio -i

jQuery Ajax POST example with PHP

Pure JS

In pure JS it will be much simpler

foo.onsubmit = e=> {
  e.preventDefault();
  fetch(foo.action,{method:'post', body: new FormData(foo)});
}

_x000D_
_x000D_
foo.onsubmit = e=> {
  e.preventDefault();
  fetch(foo.action,{method:'post', body: new FormData(foo)});
}
_x000D_
<form name="foo" action="form.php" method="POST" id="foo">
    <label for="bar">A bar</label>
    <input id="bar" name="bar" type="text" value="" />
    <input type="submit" value="Send" />
</form>
_x000D_
_x000D_
_x000D_

Create a HTML table where each TR is a FORM

If you can use javascript and strictly require it on your web, you can put textboxes, checkboxes and whatever on each row of your table and at the end of each row place button (or link of class rowSubmit) "save". Without any FORM tag. Form than will be simulated by JS and Ajax like this:

<script type="text/javascript">
$(document).ready(function(){
  $(".rowSubmit").click(function()
  {
     var form = '<form><table><tr>' + $(this).closest('tr').html() + '</tr></table></form>';
     var serialized = $(form).serialize(); 
     $.get('url2action', serialized, function(data){
       // ... can be empty
     }); 
   });
});        
</script>

What do you think?

PS: If you write in jQuery this:

$("valid HTML string")
$(variableWithValidHtmlString)

It will be turned into jQuery object and you can work with it as you are used to in jQuery.

How to set only time part of a DateTime variable in C#

date = new DateTime(date.year, date.month, date.day, HH, MM, SS);

Display help message with python argparse when script is called without any arguments

Set your positional arguments with nargs, and check if positional args are empty.

import argparse
parser = argparse.ArgumentParser()
parser.add_argument('file', nargs='?')
args = parser.parse_args()
if not args.file:
    parser.print_help()

Reference Python nargs

How can I execute Python scripts using Anaconda's version of Python?

The instructions in the official Python documentation worked for me: https://docs.python.org/2/using/windows.html#executing-scripts

  1. Launch a command prompt.

  2. Associate the correct file group with .py scripts:

    assoc .py=Python.File
    

Redirect all Python files to the new executable:

    ftype Python.File=C:\Path\to\pythonw.exe "%1" %*

The example shows how to associate the .py extension with the .pyw executable, but it works if you want to associate the .py extension with the Anaconda Python executable. You need administrative rights. The name "Python.File" could be anything, you just have to make sure is the same name in the ftype command. When you finish and before you try double-clicking the .py file, you must change the "Open with" in the file properties. The file type will be now ".py" and it is opened with the Anaconda python.exe.

How to change Vagrant 'default' machine name?

In case there are many people using your vagrant file - you might want to set name dynamically. Below is the example how to do it using username from your HOST machine as the name of the box and hostname:

require 'etc'
vagrant_name = "yourProjectName-" + Etc.getlogin
Vagrant.configure("2") do |config|
  config.vm.box = "ubuntu/xenial64"
  config.vm.hostname = vagrant_name
  config.vm.provider "virtualbox" do |v|
    v.name = vagrant_name
  end
end

Found conflicts between different versions of the same dependent assembly that could not be resolved

Please note that I solved this problem by putting the AutoGenerateBindingRedirects right after the TargetFramework in the csproj file:

<TargetFramework>net462</TargetFramework>
<AutoGenerateBindingRedirects>true</AutoGenerateBindingRedirects>

How to crop an image in OpenCV using Python

Alternatively, you could use tensorflow for the cropping and openCV for making an array from the image.

import cv2
img = cv2.imread('YOURIMAGE.png')

Now img is a (imageheight, imagewidth, 3) shape array. Crop the array with tensorflow:

import tensorflow as tf
offset_height=0
offset_width=0
target_height=500
target_width=500
x = tf.image.crop_to_bounding_box(
    img, offset_height, offset_width, target_height, target_width
)

Reassemble the image with tf.keras, so we can look at it if it worked:

tf.keras.preprocessing.image.array_to_img(
    x, data_format=None, scale=True, dtype=None
)

This prints out the pic in a notebook (tested in Google Colab).


The whole code together:

import cv2
img = cv2.imread('YOURIMAGE.png')

import tensorflow as tf
offset_height=0
offset_width=0
target_height=500
target_width=500
x = tf.image.crop_to_bounding_box(
    img, offset_height, offset_width, target_height, target_width
)

tf.keras.preprocessing.image.array_to_img(
    x, data_format=None, scale=True, dtype=None
)

How to convert an XML file to nice pandas dataframe?

You can also convert by creating a dictionary of elements and then directly converting to a data frame:

import xml.etree.ElementTree as ET
import pandas as pd

# Contents of test.xml
# <?xml version="1.0" encoding="utf-8"?> <tags>   <row Id="1" TagName="bayesian" Count="4699" ExcerptPostId="20258" WikiPostId="20257" />   <row Id="2" TagName="prior" Count="598" ExcerptPostId="62158" WikiPostId="62157" />   <row Id="3" TagName="elicitation" Count="10" />   <row Id="5" TagName="open-source" Count="16" /> </tags>

root = ET.parse('test.xml').getroot()

tags = {"tags":[]}
for elem in root:
    tag = {}
    tag["Id"] = elem.attrib['Id']
    tag["TagName"] = elem.attrib['TagName']
    tag["Count"] = elem.attrib['Count']
    tags["tags"]. append(tag)

df_users = pd.DataFrame(tags["tags"])
df_users.head()

How to redirect DNS to different ports

You can use SRV records:

_service._proto.name. TTL class SRV priority weight port target.

Service: the symbolic name of the desired service.

Proto: the transport protocol of the desired service; this is usually either TCP or UDP.

Name: the domain name for which this record is valid, ending in a dot.

TTL: standard DNS time to live field.

Class: standard DNS class field (this is always IN).

Priority: the priority of the target host, lower value means more preferred.

Weight: A relative weight for records with the same priority.

Port: the TCP or UDP port on which the service is to be found.

Target: the canonical hostname of the machine providing the service, ending in a dot.

Example:

_sip._tcp.example.com. 86400 IN SRV 0 5 5060 sipserver.example.com.

So what I think you're looking for is to add something like this to your DNS hosts file:

_sip._tcp.arboristal.com. 86400 IN SRV 10 40 25565 mc.arboristal.com.
_sip._tcp.arboristal.com. 86400 IN SRV 10 30 25566 tekkit.arboristal.com.
_sip._tcp.arboristal.com. 86400 IN SRV 10 30 25567 pvp.arboristal.com.

On a side note, I highly recommend you go with a hosting company rather than hosting the servers yourself. It's just asking for trouble with your home connection (DDoS and Bandwidth/Connection Speed), but it's up to you.

Define an <img>'s src attribute in CSS

No. The closest you can get is setting a background image:

<div id="myimage"></div>

#myimage {
  width: 20px;
  height: 20px;
  background: white url(myimage.gif) no-repeat;
}

How can I selectively escape percent (%) in Python strings?

Alternatively, as of Python 2.6, you can use new string formatting (described in PEP 3101):

'Print percent % in sentence and not {0}'.format(test)

which is especially handy as your strings get more complicated.

JavaScript regex for alphanumeric string with length of 3-5 chars

First this script test the strings N having chars from 3 to 5.

For multi language (arabic, Ukrainian) you Must use this

var regex = /^([a-zA-Z0-9_-\u0600-\u065f\u066a-\u06EF\u06fa-\u06ff\ufb8a\u067e\u0686\u06af\u0750-\u077f\ufb50-\ufbc1\ufbd3-\ufd3f\ufd50-\ufd8f\ufd92-\ufdc7\ufe70-\ufefc\uFDF0-\uFDFD]+){3,5}$/;  regex.test('?????');

Other wise the below is for English Alphannumeric only

/^([a-zA-Z0-9_-]){3,5}$/

P.S the above dose not accept special characters

one final thing the above dose not take space as test it will fail if there is space if you want space then add after the 0-9\s

\s

And if you want to check lenght of all string add dot .

var regex = /^([a-zA-Z0-9\s@,!=%$#&_-\u0600-\u065f\u066a-\u06EF\u06fa-\u06ff\ufb8a\u067e\u0686\u06af\u0750-\u077f\ufb50-\ufbc1\ufbd3-\ufd3f\ufd50-\ufd8f\ufd92-\ufdc7\ufe70-\ufefc\uFDF0-\uFDFD]).{1,30}$/;

How to present popover properly in iOS 8

Here i Convert "Joris416" Swift Code to Objective-c,

-(void) popoverstart
{
    ViewController *controller = [self.storyboard instantiateViewControllerWithIdentifier:@"PopoverView"];
    UINavigationController *nav = [[UINavigationController alloc]initWithRootViewController:controller];
    nav.modalPresentationStyle = UIModalPresentationPopover;
    UIPopoverPresentationController *popover = nav.popoverPresentationController;
    controller.preferredContentSize = CGSizeMake(300, 200);
    popover.delegate = self;
    popover.sourceView = self.view;
    popover.sourceRect = CGRectMake(100, 100, 0, 0);
    popover.permittedArrowDirections = UIPopoverArrowDirectionAny;
    [self presentViewController:nav animated:YES completion:nil];
}

-(UIModalPresentationStyle) adaptivePresentationStyleForPresentationController: (UIPresentationController * ) controller
{
    return UIModalPresentationNone;
}

Remember to ADD
UIPopoverPresentationControllerDelegate, UIAdaptivePresentationControllerDelegate

MVC: How to Return a String as JSON

Use the following code in your controller:

return Json(new { success = string }, JsonRequestBehavior.AllowGet);

and in JavaScript:

success: function (data) {
    var response = data.success;
    ....
}

Adding minutes to date time in PHP

Use strtotime("+5 minute", $date);


Example:

$date = "2017-06-16 08:40:00";
$date = strtotime($date);
$date = strtotime("+5 minute", $date);
echo date('Y-m-d H:i:s', $date);

ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use

Execute dump query in terminal then it will work

mysql -u root -p  <Database_Name> > <path of the input file>

Why do you need ./ (dot-slash) before executable or script name to run it in bash?

Your script, when in your home directory will not be found when the shell looks at the $PATH environment variable to find your script.

The ./ says 'look in the current directory for my script rather than looking at all the directories specified in $PATH'.

How to perform an SQLite query within an Android application?

This will also work if the pattern you want to match is a variable.

dbh = new DbHelper(this);
SQLiteDatabase db = dbh.getWritableDatabase();

Cursor c = db.query(
    "TableName", 
    new String[]{"ColumnName"}, 
    "ColumnName LIKE ?", 
    new String[]{_data+"%"}, 
    null, 
    null, 
    null
);

while(c.moveToNext()){
    // your calculation goes here
}

Is it possible to decrypt MD5 hashes?

You can't - in theory. The whole point of a hash is that it's one way only. This means that if someone manages to get the list of hashes, they still can't get your password. Additionally it means that even if someone uses the same password on multiple sites (yes, we all know we shouldn't, but...) anyone with access to the database of site A won't be able to use the user's password on site B.

The fact that MD5 is a hash also means it loses information. For any given MD5 hash, if you allow passwords of arbitrary length there could be multiple passwords which produce the same hash. For a good hash it would be computationally infeasible to find them beyond a pretty trivial maximum length, but it means there's no guarantee that if you find a password which has the target hash, it's definitely the original password. It's astronomically unlikely that you'd see two ASCII-only, reasonable-length passwords that have the same MD5 hash, but it's not impossible.

MD5 is a bad hash to use for passwords:

  • It's fast, which means if you have a "target" hash, it's cheap to try lots of passwords and see whether you can find one which hashes to that target. Salting doesn't help with that scenario, but it helps to make it more expensive to try to find a password matching any one of multiple hashes using different salts.
  • I believe it has known flaws which make it easier to find collisions, although finding collisions within printable text (rather than arbitrary binary data) would at least be harder.

I'm not a security expert, so won't make a concrete recommendation beyond "Don't roll your own authentication system." Find one from a reputable supplier, and use that. Both the design and implementation of security systems is a tricky business.

How to create Gmail filter searching for text only at start of subject line?

I was wondering how to do this myself; it seems Gmail has since silently implemented this feature. I created the following filter:

Matches: subject:([test])
Do this: Skip Inbox

And then I sent a message with the subject

[test] foo

And the message was archived! So it seems all that is necessary is to create a filter for the subject prefix you wish to handle.

How to print a certain line of a file with PowerShell?

You can use the -TotalCount parameter of the Get-Content cmdlet to read the first n lines, then use Select-Object to return only the nth line:

Get-Content file.txt -TotalCount 9 | Select-Object -Last 1;

Per the comment from @C.B. this should improve performance by only reading up to and including the nth line, rather than the entire file. Note that you can use the aliases -First or -Head in place of -TotalCount.

adb shell su works but adb root does not

I use for enter su mode in abd shell

adb shell "su"

open_basedir restriction in effect. File(/) is not within the allowed path(s):

I am using an Apache vhost-File to run PHP with application-specific ini-options on my windows-server. Therefore I use the -d option of the php-command.

I am setting the open_basedir for every application as one of these options.

I needed to set multiple urls as open_basedir, including an UNC-Path, and the syntax for this case was a bit hard to find. You have to seperate the paths with semicolons and if your first path starts with a driveletter you might have to start the list with a semicolon too. At least that's what works for me.

Example:

php.exe -d open_basedir=;d:/www/applicationRoot;//internal.unc.path/ressource/

No module named pkg_resources

If you are encountering this issue with an application installed via conda, the solution (as stated in this bug report) is simply to install setup-tools with:

conda install setuptools

Python constructors and __init__

coonstructors are called automatically when you create a new object, thereby "constructing" the object. The reason you can have more than one init is because names are just references in python, and you are allowed to change what each variable references whenever you want (hence dynamic typing)

def func(): #now func refers to an empty funcion
    pass
...
func=5      #now func refers to the number 5
def func():
    print "something"    #now func refers to a different function

in your class definition, it just keeps the later one

What is the Simplest Way to Reverse an ArrayList?

A little more readable :)

public static <T> ArrayList<T> reverse(ArrayList<T> list) {
    int length = list.size();
    ArrayList<T> result = new ArrayList<T>(length);

    for (int i = length - 1; i >= 0; i--) {
        result.add(list.get(i));
    }

    return result;
}

Why am I getting a " Traceback (most recent call last):" error?

At the beginning of your file you set raw_input to 0. Do not do this, at it modifies the built-in raw_input() function. Therefore, whenever you call raw_input(), it is essentially calling 0(), which raises the error. To remove the error, remove the first line of your code:

M = 1.6
# Miles to Kilometers 
# Celsius Celsius = (var1 - 32) * 5/9
# Gallons to liters Gallons = 3.6
# Pounds to kilograms Pounds = 0.45
# Inches to centimete Inches = 2.54


def intro():
    print("Welcome! This program will convert measures for you.")
    main()

def main():
    print("Select operation.")
    print("1.Miles to Kilometers")
    print("2.Fahrenheit to Celsius")
    print("3.Gallons to liters")
    print("4.Pounds to kilograms")
    print("5.Inches to centimeters")

    choice = input("Enter your choice by number: ")

    if choice == '1':
        convertMK()

    elif choice == '2':
        converCF()

    elif choice == '3':
        convertGL()

    elif choice == '4':
        convertPK()

    elif choice == '5':
        convertPK()

    else:
        print("Error")


def convertMK():
    input_M = float(raw_input(("Miles: ")))
    M_conv = (M) * input_M
    print("Kilometers: %f\n" % M_conv)
    restart = str(input("Do you wish to make another conversion? [y]Yes or [n]no: "))
    if restart == 'y':
        main()
    elif restart == 'n':
        end()
    else:
        print("I didn't quite understand that answer. Terminating.")
        main()

def converCF():
    input_F = float(raw_input(("Fahrenheit: ")))
    F_conv = (input_F - 32) * 5/9
    print("Celcius: %f\n") % F_conv
    restart = str(input("Do you wish to make another conversion? [y]Yes or [n]no: "))
    if restart == 'y':
        main()
    elif restart == 'n':
        end()
    else:
        print("I didn't quite understand that answer. Terminating.")
        main()

def convertGL():
    input_G = float(raw_input(("Gallons: ")))
    G_conv = input_G * 3.6
    print("Centimeters: %f\n" % G_conv)
    restart = str(input("Do you wish to make another conversion? [y]Yes or [n]no: "))
    if restart == 'y':
        main()
    elif restart == 'n':
        end()
    else:
        print ("I didn't quite understand that answer. Terminating.")
        main()

def convertPK():
    input_P = float(raw_input(("Pounds: ")))
    P_conv = input_P * 0.45
    print("Centimeters: %f\n" % P_conv)
    restart = str(input("Do you wish to make another conversion? [y]Yes or [n]no: "))
    if restart == 'y':
        main()
    elif restart == 'n':
        end()
    else:
        print ("I didn't quite understand that answer. Terminating.")
        main()

def convertIC():
    input_cm = float(raw_input(("Inches: ")))
    inches_conv = input_cm * 2.54
    print("Centimeters: %f\n" % inches_conv)
    restart = str(input("Do you wish to make another conversion? [y]Yes or [n]no: "))
    if restart == 'y':
        main()
    elif restart == 'n':
        end()
    else:
        print ("I didn't quite understand that answer. Terminating.")
        main()

def end():
    print("This program will close.")
    exit()

intro()

What's the fastest way of checking if a point is inside a polygon in python

Your test is good, but it measures only some specific situation: we have one polygon with many vertices, and long array of points to check them within polygon.

Moreover, I suppose that you're measuring not matplotlib-inside-polygon-method vs ray-method, but matplotlib-somehow-optimized-iteration vs simple-list-iteration

Let's make N independent comparisons (N pairs of point and polygon)?

# ... your code...
lenpoly = 100
polygon = [[np.sin(x)+0.5,np.cos(x)+0.5] for x in np.linspace(0,2*np.pi,lenpoly)[:-1]]

M = 10000
start_time = time()
# Ray tracing
for i in range(M):
    x,y = np.random.random(), np.random.random()
    inside1 = ray_tracing_method(x,y, polygon)
print "Ray Tracing Elapsed time: " + str(time()-start_time)

# Matplotlib mplPath
start_time = time()
for i in range(M):
    x,y = np.random.random(), np.random.random()
    inside2 = path.contains_points([[x,y]])
print "Matplotlib contains_points Elapsed time: " + str(time()-start_time)

Result:

Ray Tracing Elapsed time: 0.548588991165
Matplotlib contains_points Elapsed time: 0.103765010834

Matplotlib is still much better, but not 100 times better. Now let's try much simpler polygon...

lenpoly = 5
# ... same code

result:

Ray Tracing Elapsed time: 0.0727779865265
Matplotlib contains_points Elapsed time: 0.105288982391

Detect current device with UI_USER_INTERFACE_IDIOM() in Swift

Since iOS 13, UI_USER_INTERFACE_IDIOM has been deprecated. If your code is still in Obj-C, you can use the following:

if (UIDevice.currentDevice.userInterfaceIdiom == UIUserInterfaceIdiomPad) {
    // device is iPad
}

Where:

typedef NS_ENUM(NSInteger, UIUserInterfaceIdiom) {
    UIUserInterfaceIdiomUnspecified = -1,
    UIUserInterfaceIdiomPhone API_AVAILABLE(ios(3.2)), // iPhone and iPod touch style UI
    UIUserInterfaceIdiomPad API_AVAILABLE(ios(3.2)), // iPad style UI
    UIUserInterfaceIdiomTV API_AVAILABLE(ios(9.0)), // Apple TV style UI
    UIUserInterfaceIdiomCarPlay API_AVAILABLE(ios(9.0)), // CarPlay style UI
};

Difference between scaling horizontally and vertically for databases

There is an additional architecture that wasn't mentioned - SQL-based database services that enable horizontal scaling without the complexity of manual sharding. These services do the sharding in the background, so they enable you to run a traditional SQL database and scale out like you would with NoSQL engines like MongoDB or CouchDB. Two services I am familiar with are EnterpriseDB for PostgreSQL and Xeround for MySQL. I saw an in-depth post by Xeround which explains why scale-out on SQL databases is difficult and how they do it differently - treat this with a grain of salt as it is a vendor post. Also check out Wikipedia's Cloud Database entry, there is a nice explanation of SQL vs. NoSQL and service vs. self-hosted, a list of vendors and scaling options for each combination. ;)

Is it possible to use jQuery .on and hover?

None of these solutions worked for me when mousing over/out of objects created after the document has loaded as the question requests. I know this question is old but I have a solution for those still looking:

$("#container").on('mouseenter', '.selector', function() {
    //do something
});
$("#container").on('mouseleave', '.selector', function() {
    //do something
});

This will bind the functions to the selector so that objects with this selector made after the document is ready will still be able to call it.

What does -1 mean in numpy reshape?

The final outcome of the conversion is that the number of elements in the final array is same as that of the initial array or data frame.

-1 corresponds to the unknown count of the row or column. We can think of it as x(unknown). x is obtained by dividing the number of elements in the original array by the other value of the ordered pair with -1.

Examples:

12 elements with reshape(-1,1) corresponds to an array with x=12/1=12 rows and 1 column.


12 elements with reshape(1,-1) corresponds to an array with 1 row and x=12/1=12 columns.

How do I tell if a regular file does not exist in Bash?

Bash File Testing

-b filename - Block special file
-c filename - Special character file
-d directoryname - Check for directory Existence
-e filename - Check for file existence, regardless of type (node, directory, socket, etc.)
-f filename - Check for regular file existence not a directory
-G filename - Check if file exists and is owned by effective group ID
-G filename set-group-id - True if file exists and is set-group-id
-k filename - Sticky bit
-L filename - Symbolic link
-O filename - True if file exists and is owned by the effective user id
-r filename - Check if file is a readable
-S filename - Check if file is socket
-s filename - Check if file is nonzero size
-u filename - Check if file set-user-id bit is set
-w filename - Check if file is writable
-x filename - Check if file is executable

How to use:

#!/bin/bash
file=./file
if [ -e "$file" ]; then
    echo "File exists"
else 
    echo "File does not exist"
fi 

A test expression can be negated by using the ! operator

#!/bin/bash
file=./file
if [ ! -e "$file" ]; then
    echo "File does not exist"
else 
    echo "File exists"
fi 

go get results in 'terminal prompts disabled' error for github private repo

I found this extremely helpful, and it solved my problem. This command will allow your 2FA to do its thing (and save you the trouble of entering your username and password):

git config --global --add url."[email protected]:".insteadOf "https://github.com/"

Source: http://albertech.blogspot.com/2016/11/fix-git-error-could-not-read-username.html

If you're not using 2FA, you can still use SSH and this will work.

Edit: added the --add flag as suggested by slatunje.

How to reload .bash_profile from the command line?

. ~/.bash_profile

Just make sure you don't have any dependencies on the current state in there.

Getting query parameters from react-router hash fragment

OLD (pre v4):

Writing in es6 and using react 0.14.6 / react-router 2.0.0-rc5. I use this command to lookup the query params in my components:

this.props.location.query

It creates a hash of all available query params in the url.

UPDATE (React Router v4+):

this.props.location.query in React Router 4 has been removed (currently using v4.1.1) more about the issue here: https://github.com/ReactTraining/react-router/issues/4410

Looks like they want you to use your own method to parse the query params, currently using this library to fill the gap: https://github.com/sindresorhus/query-string

Absolute Positioning & Text Alignment

The div doesn't take up all the available horizontal space when absolutely positioned. Explicitly setting the width to 100% will solve the problem:

HTML

<div id="my-div">I want to be centered</div>?

CSS

#my-div {
   position: absolute;
   bottom: 15px;
   text-align: center;
   width: 100%;
}

?

How to launch an application from a browser?

I achieved the same thing using a local web server and PHP. I used a script containing shell_exec to launch an application locally.

Alternatively, you could do something like this:

<a href="file://C:/Windows/notepad.exe">Notepad</a>

Chrome DevTools Devices does not detect device when plugged in

If you're on windows, you need to install the drivers for your phone. You can get them here.

If it still doesn't work, I've had luck connecting by manually restarting the Android Debug Bridge manually. More info is here.

Html table with button on each row

Put a single listener on the table. When it gets a click from an input with a button that has a name of "edit" and value "edit", change its value to "modify". Get rid of the input's id (they aren't used for anything here), or make them all unique.

<script type="text/javascript">

function handleClick(evt) {
  var node = evt.target || evt.srcElement;
  if (node.name == 'edit') {
    node.value = "Modify";
  }
}

</script>

<table id="table1" border="1" onclick="handleClick(event);">
    <thead>
      <tr>
          <th>Select
    </thead>
    <tbody>
       <tr> 
           <td>
               <form name="f1" action="#" >
                <input id="edit1" type="submit" name="edit" value="Edit">
               </form>
       <tr> 
           <td>
               <form name="f2" action="#" >
                <input id="edit2" type="submit" name="edit" value="Edit">
               </form>
       <tr> 
           <td>
               <form name="f3" action="#" >
                <input id="edit3" type="submit" name="edit" value="Edit">
               </form>

   </tbody>
</table>

Build Step Progress Bar (css and jquery)

What I would do is use the same trick often use for hovering on buttons. Prepare an image that has 2 parts: (1) a top half which is greyed out, meaning incomplete, and (2) a bottom half which is colored in, meaning completed. Use the same image 4 times to make up the 4 steps of the progress bar, and align top for incomplete steps, and align bottom for incomplete steps.

In order to take advantage of image alignment, you'd have to use the image as the background for 4 divs, rather than using the img element.

This is the CSS for background image alignment:

div.progress-incomplete {
  background-position: top;
}
div.progress-finished {
  background-position: bottom;
}

Fastest way to check if a value exists in a list

def check_availability(element, collection: iter):
    return element in collection

Usage

check_availability('a', [1,2,3,4,'a','b','c'])

I believe this is the fastest way to know if a chosen value is in an array.

What is the best way to calculate a checksum for a file that is on my machine?

Note that the above solutions will not tell you if your installation is correct only if your install.exe is correct (you can trust it to produce a correct install.)

You would need MD5 sums for each file/folder to test if the installed code has been messed with after the install completed.

WinMerg is useful to compare two installs (on two different machines perhaps) to see if one has been changed or why one is broken.

Why does adb return offline after the device string?

I post here my question just in case is helpful for somebody else. My problem was that my colleague was connected to the same device and I was not able to connect to the same device.

Note: I had this problem with Amazon Fire TV connecting over Wifi.

There are 2 solutions:

Easy to "drop" his connection (sorry buddy :)

Restart the device
adb kill-server
adb start-server
adb connect device-ip

A bit more difficult but two clients can use the same device (use different TCP ports)

Please look at this answer

Vector of Vectors to create matrix

Vector needs to be initialized before using it as cin>>v[i][j]. Even if it was 1D vector, it still needs an initialization, see this link

After initialization there will be no errors, see this link

Find methods calls in Eclipse project

Right click on method and click on Open call Hierarchy

eclipse right click call hierarchy

How to playback MKV video in web browser?

HTML5 and the VLC web plugin were a no go for me but I was able to get this work using the following setup:

DivX Web Player (NPAPI browsers only)

AC3 Audio Decoder

And here is the HTML:

<embed id="divxplayer" type="video/divx" width="1024" height="768" 
src ="path_to_file" autoPlay=\"true\" 
pluginspage=\"http://go.divx.com/plugin/download/\"></embed>

The DivX player seems to allow for a much wider array of video and audio options than the native HTML5, so far I am very impressed by it.

How to align input forms in HTML

You should use a table. As a matter of logical structure the data is tabular: this is why you want it to align, because you want to show that the labels are not related solely to their input boxes but also to each other, in a two-dimensional structure.

[consider what you would do if you had string or numeric values to display instead of input boxes.]

Export from pandas to_excel without row names (index)?

Example: index = False

import pandas as pd

writer = pd.ExcelWriter("dataframe.xlsx", engine='xlsxwriter')
dataframe.to_excel(writer,sheet_name = dataframe, index=False)
writer.save() 

Convert UTC date time to local date time

After trying a few others posted here without good results, this seemed to work for me:

convertUTCDateToLocalDate: function (date) {
    return new Date(Date.UTC(date.getFullYear(), date.getMonth(), date.getDate(),  date.getHours(), date.getMinutes(), date.getSeconds()));
}

And this works to go the opposite way, from Local Date to UTC:

convertLocalDatetoUTCDate: function(date){
    return new Date(date.getUTCFullYear(), date.getUTCMonth(), date.getUTCDate(),  date.getUTCHours(), date.getUTCMinutes(), date.getUTCSeconds());
}

What is (x & 1) and (x >>= 1)?

These are Bitwise Operators (reference).

x & 1 produces a value that is either 1 or 0, depending on the least significant bit of x: if the last bit is 1, the result of x & 1 is 1; otherwise, it is 0. This is a bitwise AND operation.

x >>= 1 means "set x to itself shifted by one bit to the right". The expression evaluates to the new value of x after the shift.

Note: The value of the most significant bit after the shift is zero for values of unsigned type. For values of signed type the most significant bit is copied from the sign bit of the value prior to shifting as part of sign extension, so the loop will never finish if x is a signed type, and the initial value is negative.

How to allow user to pick the image with Swift?

You can do like here

var avatarImageView = UIImageView()
var imagePicker = UIImagePickerController()
        
func takePhotoFromGallery() {
    imagePicker.delegate = self
    imagePicker.sourceType = .savedPhotosAlbum
    imagePicker.allowsEditing = true
    
    present(imagePicker, animated: true)
}

func imagePickerController(_ picker: UIImagePickerController,
                           didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {
    if let pickedImage = info[.originalImage] as? UIImage {
        avatarImageView.contentMode = .scaleAspectFill
        avatarImageView.image = pickedImage
    }
    self.dismiss(animated: true)
}

Hope this was helpful

How can I convert a string to upper- or lower-case with XSLT?

In XSLT 1.0 the upper-case() and lower-case() functions are not available. If you're using a 1.0 stylesheet the common method of case conversion is translate():

<xsl:variable name="lowercase" select="'abcdefghijklmnopqrstuvwxyz'" />
<xsl:variable name="uppercase" select="'ABCDEFGHIJKLMNOPQRSTUVWXYZ'" />


<xsl:template match="/">
  <xsl:value-of select="translate(doc, $lowercase, $uppercase)" />
</xsl:template>

How do I write to a Python subprocess' stdin?

To clarify some points:

As jro has mentioned, the right way is to use subprocess.communicate.

Yet, when feeding the stdin using subprocess.communicate with input, you need to initiate the subprocess with stdin=subprocess.PIPE according to the docs.

Note that if you want to send data to the process’s stdin, you need to create the Popen object with stdin=PIPE. Similarly, to get anything other than None in the result tuple, you need to give stdout=PIPE and/or stderr=PIPE too.

Also qed has mentioned in the comments that for Python 3.4 you need to encode the string, meaning you need to pass Bytes to the input rather than a string. This is not entirely true. According to the docs, if the streams were opened in text mode, the input should be a string (source is the same page).

If streams were opened in text mode, input must be a string. Otherwise, it must be bytes.

So, if the streams were not opened explicitly in text mode, then something like below should work:

import subprocess
command = ['myapp', '--arg1', 'value_for_arg1']
p = subprocess.Popen(command, stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
output = p.communicate(input='some data'.encode())[0]

I've left the stderr value above deliberately as STDOUT as an example.

That being said, sometimes you might want the output of another process rather than building it up from scratch. Let's say you want to run the equivalent of echo -n 'CATCH\nme' | grep -i catch | wc -m. This should normally return the number characters in 'CATCH' plus a newline character, which results in 6. The point of the echo here is to feed the CATCH\nme data to grep. So we can feed the data to grep with stdin in the Python subprocess chain as a variable, and then pass the stdout as a PIPE to the wc process' stdin (in the meantime, get rid of the extra newline character):

import subprocess

what_to_catch = 'catch'
what_to_feed = 'CATCH\nme'

# We create the first subprocess, note that we need stdin=PIPE and stdout=PIPE
p1 = subprocess.Popen(['grep', '-i', what_to_catch], stdin=subprocess.PIPE, stdout=subprocess.PIPE)

# We immediately run the first subprocess and get the result
# Note that we encode the data, otherwise we'd get a TypeError
p1_out = p1.communicate(input=what_to_feed.encode())[0]

# Well the result includes an '\n' at the end, 
# if we want to get rid of it in a VERY hacky way
p1_out = p1_out.decode().strip().encode()

# We create the second subprocess, note that we need stdin=PIPE
p2 = subprocess.Popen(['wc', '-m'], stdin=subprocess.PIPE, stdout=subprocess.PIPE)

# We run the second subprocess feeding it with the first subprocess' output.
# We decode the output to convert to a string
# We still have a '\n', so we strip that out
output = p2.communicate(input=p1_out)[0].decode().strip()

This is somewhat different than the response here, where you pipe two processes directly without adding data directly in Python.

Hope that helps someone out.

Using CSS in Laravel views?

For those who need to keep js/css out of public folder for whatever reasons, in modern Laravel you can use sub-views. Say your views structure is

views
    view1.blade.php
    view1-css.blade.php
    view1-js1.blade.php
    view1-js2.blade.php

in view1 add

@include('view1-css')
@include('view1-js1')
@include('view1-js2')

in views-js.blade.php files wrap your js code in <script> tag

in views-css.blade.php wrap your styles in <style> tag

That will tell Laravel, and your code editor, that those are in fact js and css files. You can do the same with additional HTML, SVGs and other stuff that is browser-renderable

Get Date in YYYYMMDD format in windows batch file

You can try this ! This should work on windows machines.

for /F "usebackq tokens=1,2,3 delims=-" %%I IN (`echo %date%`) do echo "%%I" "%%J" "%%K"

Classpath including JAR within a JAR

I use maven for my java builds which has a plugin called the maven assembly plugin.

It does what your asking, but like some of the other suggestions describe - essentially exploding all the dependent jars and recombining them into a single jar

javax.net.ssl.SSLException: Received fatal alert: protocol_version

This seems like a protocol version mismatch, this exception normally happens when there is a mismatch between SSL protocol version used by the client and the server. your clients should use a proctocol version supported by the server.

How do I convert an object to an array?

Simple version:

$arrayObject = new ArrayObject($object);
$array = $arrayObject->getArrayCopy();

Updated recursive version:

class RecursiveArrayObject extends ArrayObject
{
    function getArrayCopy()
    {
        $resultArray = parent::getArrayCopy();
        foreach($resultArray as $key => $val) {
            if (!is_object($val)) {
                continue;
            }
            $o = new RecursiveArrayObject($val);
            $resultArray[$key] = $o->getArrayCopy();
        }
        return $resultArray;
    }
}

$arrayObject = new RecursiveArrayObject($object);
$array = $arrayObject->getArrayCopy();

How to query between two dates using Laravel and Eloquent?

Another option if your field is datetime instead of date (although it works for both cases):

$fromDate = "2016-10-01";
$toDate   = "2016-10-31";

$reservations = Reservation::whereRaw(
  "(reservation_from >= ? AND reservation_from <= ?)", 
  [$fromDate." 00:00:00", $toDate." 23:59:59"]
)->get();

Downloading an entire S3 bucket?

I've used a few different methods to copy Amazon S3 data to a local machine, including s3cmd, and by far the easiest is Cyberduck.

All you need to do is enter your Amazon credentials and use the simple interface to download, upload, sync any of your buckets, folders or files.

Screenshot

How do you express binary literals in Python?

For reference—future Python possibilities:
Starting with Python 2.6 you can express binary literals using the prefix 0b or 0B:

>>> 0b101111
47

You can also use the new bin function to get the binary representation of a number:

>>> bin(173)
'0b10101101'

Development version of the documentation: What's New in Python 2.6

How do you convert a JavaScript date to UTC?

Using moment package, you can easily convert a date string of UTC to a new Date object:

const moment = require('moment');
let b = new Date(moment.utc('2014-02-20 00:00:00.000000'));
let utc = b.toUTCString();
b.getTime();

This specially helps when your server do not support timezone and you want to store UTC date always in server and get it back as a new Date object. Above code worked for my requirement of similar issue that this thread is for. Sharing here so that it can help others. I do not see exactly above solution in any answer. Thanks.

Storyboard doesn't contain a view controller with identifier

Fixed! Not only the identifier in the segue must be set, in my case DrivingDetails, but also the identifier in my tableViewController must be set as DrivingDetails...check my picture:

enter image description here

I also removed the navigation view controller so now the 2 table view controllers are connected directly with a "push" animation.

*****EDIT for XCODE 7.0*****

you have to set the storyboardId(in this case the viewController is embedded in a Navigation controller:

let lastMinVc  = mainStoryBoard.instantiateViewControllerWithIdentifier("lastMinuteNavController") as! UINavigationController

enter image description here

Format an Excel column (or cell) as Text in C#?

Solution that worked for me for Excel Interop:

myWorksheet.Columns[j].NumberFormat = "@";      // column as a text
myWorksheet.Cells[i + 2, j].NumberFormat = "@"; // cell as a text

This code should run before putting data to Excel. Column and row numbers are 1-based.

A bit more details. Whereas accepted response with reference for SpreadsheetGear looks almost correct, I had two concerns about it:

  1. I am not using SpreadsheetGear. I was interested in regular Excel communication thru Excel interop without any 3rdparty libraries,
  2. I was searching for the way to format column by number, not using ranges like "A:A".

What is the difference between Step Into and Step Over in a debugger

Consider the following code with your current instruction pointer (the line that will be executed next, indicated by ->) at the f(x) line in g(), having been called by the g(2) line in main():

public class testprog {
    static void f (int x) {
        System.out.println ("num is " + (x+0)); // <- STEP INTO
    }

    static void g (int x) {
->      f(x); //
        f(1); // <----------------------------------- STEP OVER
    }

    public static void main (String args[]) {
        g(2);
        g(3); // <----------------------------------- STEP OUT OF
    }
}

If you were to step into at that point, you will move to the println() line in f(), stepping into the function call.

If you were to step over at that point, you will move to the f(1) line in g(), stepping over the function call.

Another useful feature of debuggers is the step out of or step return. In that case, a step return will basically run you through the current function until you go back up one level. In other words, it will step through f(x) and f(1), then back out to the calling function to end up at g(3) in main().

How to create a fixed-size array of objects

Fixed-length arrays are not yet supported. What does that actually mean? Not that you can't create an array of n many things — obviously you can just do let a = [ 1, 2, 3 ] to get an array of three Ints. It means simply that array size is not something that you can declare as type information.

If you want an array of nils, you'll first need an array of an optional type — [SKSpriteNode?], not [SKSpriteNode] — if you declare a variable of non-optional type, whether it's an array or a single value, it cannot be nil. (Also note that [SKSpriteNode?] is different from [SKSpriteNode]?... you want an array of optionals, not an optional array.)

Swift is very explicit by design about requiring that variables be initialized, because assumptions about the content of uninitialized references are one of the ways that programs in C (and some other languages) can become buggy. So, you need to explicitly ask for an [SKSpriteNode?] array that contains 64 nils:

var sprites = [SKSpriteNode?](repeating: nil, count: 64)

This actually returns a [SKSpriteNode?]?, though: an optional array of optional sprites. (A bit odd, since init(count:,repeatedValue:) shouldn't be able to return nil.) To work with the array, you'll need to unwrap it. There's a few ways to do that, but in this case I'd favor optional binding syntax:

if var sprites = [SKSpriteNode?](repeating: nil, count: 64){
    sprites[0] = pawnSprite
}

Dictionary returning a default value if the key does not exist

I created a DefaultableDictionary to do exactly what you are asking for!

using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.ObjectModel;

namespace DefaultableDictionary {
    public class DefaultableDictionary<TKey, TValue> : IDictionary<TKey, TValue> {
        private readonly IDictionary<TKey, TValue> dictionary;
        private readonly TValue defaultValue;

        public DefaultableDictionary(IDictionary<TKey, TValue> dictionary, TValue defaultValue) {
            this.dictionary = dictionary;
            this.defaultValue = defaultValue;
        }

        public IEnumerator<KeyValuePair<TKey, TValue>> GetEnumerator() {
            return dictionary.GetEnumerator();
        }

        IEnumerator IEnumerable.GetEnumerator() {
            return GetEnumerator();
        }

        public void Add(KeyValuePair<TKey, TValue> item) {
            dictionary.Add(item);
        }

        public void Clear() {
            dictionary.Clear();
        }

        public bool Contains(KeyValuePair<TKey, TValue> item) {
            return dictionary.Contains(item);
        }

        public void CopyTo(KeyValuePair<TKey, TValue>[] array, int arrayIndex) {
            dictionary.CopyTo(array, arrayIndex);
        }

        public bool Remove(KeyValuePair<TKey, TValue> item) {
            return dictionary.Remove(item);
        }

        public int Count {
            get { return dictionary.Count; }
        }

        public bool IsReadOnly {
            get { return dictionary.IsReadOnly; }
        }

        public bool ContainsKey(TKey key) {
            return dictionary.ContainsKey(key);
        }

        public void Add(TKey key, TValue value) {
            dictionary.Add(key, value);
        }

        public bool Remove(TKey key) {
            return dictionary.Remove(key);
        }

        public bool TryGetValue(TKey key, out TValue value) {
            if (!dictionary.TryGetValue(key, out value)) {
                value = defaultValue;
            }

            return true;
        }

        public TValue this[TKey key] {
            get
            {
                try
                {
                    return dictionary[key];
                } catch (KeyNotFoundException) {
                    return defaultValue;
                }
            }

            set { dictionary[key] = value; }
        }

        public ICollection<TKey> Keys {
            get { return dictionary.Keys; }
        }

        public ICollection<TValue> Values {
            get
            {
                var values = new List<TValue>(dictionary.Values) {
                    defaultValue
                };
                return values;
            }
        }
    }

    public static class DefaultableDictionaryExtensions {
        public static IDictionary<TKey, TValue> WithDefaultValue<TValue, TKey>(this IDictionary<TKey, TValue> dictionary, TValue defaultValue ) {
            return new DefaultableDictionary<TKey, TValue>(dictionary, defaultValue);
        }
    }
}

This project is a simple decorator for an IDictionary object and an extension method to make it easy to use.

The DefaultableDictionary will allow for creating a wrapper around a dictionary that provides a default value when trying to access a key that does not exist or enumerating through all the values in an IDictionary.

Example: var dictionary = new Dictionary<string, int>().WithDefaultValue(5);

Blog post on the usage as well.

Example use of "continue" statement in Python?

I like to use continue in loops where there are a lot of contitions to be fulfilled before you get "down to business". So instead of code like this:

for x, y in zip(a, b):
    if x > y:
        z = calculate_z(x, y)
        if y - z < x:
            y = min(y, z)
            if x ** 2 - y ** 2 > 0:
                lots()
                of()
                code()
                here()

I get code like this:

for x, y in zip(a, b):
    if x <= y:
        continue
    z = calculate_z(x, y)
    if y - z >= x:
        continue
    y = min(y, z)
    if x ** 2 - y ** 2 <= 0:
        continue
    lots()
    of()
    code()
    here()

By doing it this way I avoid very deeply nested code. Also, it is easy to optimize the loop by eliminating the most frequently occurring cases first, so that I only have to deal with the infrequent but important cases (e.g. divisor is 0) when there is no other showstopper.

Last segment of URL in jquery

window.location.pathname.split("/").pop()

Take n rows from a spark dataframe and pass to toPandas()

You could get first rows of Spark DataFrame with head and then create Pandas DataFrame:

l = [('Alice', 1),('Jim',2),('Sandra',3)]
df = sqlContext.createDataFrame(l, ['name', 'age'])

df_pandas = pd.DataFrame(df.head(3), columns=df.columns)

In [4]: df_pandas
Out[4]: 
     name  age
0   Alice    1
1     Jim    2
2  Sandra    3

How to change 1 char in the string?

Merged Chuck Norris's answer w/ Paulo Mendonça's using extensions methods:

/// <summary>
/// Replace a string char at index with another char
/// </summary>
/// <param name="text">string to be replaced</param>
/// <param name="index">position of the char to be replaced</param>
/// <param name="c">replacement char</param>
public static string ReplaceAtIndex(this string text, int index, char c)
{
    var stringBuilder = new StringBuilder(text);
    stringBuilder[index] = c;
    return stringBuilder.ToString();
}

How to compile Go program consisting of multiple files?

Since Go 1.11+, GOPATH is no longer recommended, the new way is using Go Modules.

Say you're writing a program called simple:

  1. Create a directory:

    mkdir simple
    cd simple
    
  2. Create a new module:

    go mod init github.com/username/simple
    # Here, the module name is: github.com/username/simple.
    # You're free to choose any module name.
    # It doesn't matter as long as it's unique.
    # It's better to be a URL: so it can be go-gettable.
    
  3. Put all your files in that directory.

  4. Finally, run:

    go run .
    
  5. Alternatively, you can create an executable program by building it:

    go build .
    
    # then:
    ./simple     # if you're on xnix
    
    # or, just:
    simple       # if you're on Windows
    

For more information, you may read this.

Go has included support for versioned modules as proposed here since 1.11. The initial prototype vgo was announced in February 2018. In July 2018, versioned modules landed in the main Go repository. In Go 1.14, module support is considered ready for production use, and all users are encouraged to migrate to modules from other dependency management systems.

Android: where are downloaded files saved?

Most devices have some form of emulated storage. if they support sd cards they are usually mounted to /sdcard (or some variation of that name) which is usually symlinked to to a directory in /storage like /storage/sdcard0 or /storage/0 sometimes the emulated storage is mounted to /sdcard and the actual path is something like /storage/emulated/legacy. You should be able to use to get the downloads directory. You are best off using the api calls to get directories. Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS);

Since the filesystems and sdcard support varies among devices.

see similar question for more info how to access downloads folder in android?

Usually the DownloadManager handles downloads and the files are then accessed by requesting the file's uri fromthe download manager using a file id to get where file was places which would usually be somewhere in the sdcard/ real or emulated since apps can only read data from certain places on the filesystem outside of their data directory like the sdcard

How to update Xcode from command line

xCode version 11.2.1 is necessary for building app in iPad 13.2.3, When I directly try to upgrade from xcode 11.1 to 11.2.1 through App Store it get struck, So after some research , I found a solution to upgrade by removing the existing xcode from the system

So here I am adding the steps to upgrade after uninstalling existing xcode.

  1. Go to Applications and identify Xcode and drag it to trash.
  2. Empty trash to permenently delete Xcode.
  3. Now go to ~/Library/Developer/ folder and remove the contents completely Use sudo rm -rf ~/Library/Developer/ to avoid any permission issue while deleting
  4. Lastly remove any cache directory associated with xcode in the path ~/Library/Caches/com.apple.dt.Xcode sudo rm -rf ~/Library/Caches/com.apple.dt.Xcode/*
  5. After completing the above steps you can easly install xcode from App Store, which will install the current latest version of xcode

Note: Please take a backup of your existing projects before making the above changes

How to run regasm.exe from command line other than Visual Studio command prompt?

For the 64-bit RegAsm.exe you will need to find it someplace like this:

c:\Windows\Microsoft.NET\Framework64\version_number_stuff\regasm.exe

An attempt was made to access a socket in a way forbidden by its access permissions

Not surprisingly, this error can arise when another process is listening on the desired port. This happened today when I started an instance of the Apache Web server, listening on its default port (80), having forgotten that I already had IIS 7 running, and listening on that port. This is well explained in Port 80 is being used by SYSTEM (PID 4), what is that? Better yet, that article points to Stop http.sys from listening on port 80 in Windows, which explains a very simple way to resolve it, with just a tad of help from an elevated command prompt and a one-line edit of my hosts file.

How do I wrap text in a span?

Try putting your text in another div inside your span:

i.e.

<span><div>some text</div></span>

Android Gallery on Android 4.4 (KitKat) returns different URI for Intent.ACTION_GET_CONTENT

@paul burke's answer works fine for both camera and gallery pictures for API level 19 and above, but it doesn't work if your Android project's minimum SDK is set to below 19, and some answers referring above doesn't work for both gallery and camera. Well, I have modified @paul burke's code which works for API level below 19. Below is the code.

public static String getPath(final Context context, final Uri uri) {

    final boolean isKitKat = Build.VERSION.SDK_INT >=
                             Build.VERSION_CODES.KITKAT;
    Log.i("URI",uri+"");
    String result = uri+"";

    // DocumentProvider
    // if (isKitKat && DocumentsContract.isDocumentUri(context, uri)) {
    if (isKitKat && (result.contains("media.documents"))) {

        String[] ary = result.split("/");
        int length = ary.length;
        String imgary = ary[length-1];
        final String[] dat = imgary.split("%3A");

        final String docId = dat[1];
        final String type = dat[0];

        Uri contentUri = null;
        if ("image".equals(type)) {
            contentUri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI;
        }
        else if ("video".equals(type)) {
        }
        else if ("audio".equals(type)) {
        }

        final String selection = "_id=?";
        final String[] selectionArgs = new String[] {
            dat[1]
        };

        return getDataColumn(context, contentUri, selection, selectionArgs);
    }
    else
    if ("content".equalsIgnoreCase(uri.getScheme())) {
        return getDataColumn(context, uri, null, null);
    }
    // File
    else if ("file".equalsIgnoreCase(uri.getScheme())) {
        return uri.getPath();
    }

    return null;
}

public static String getDataColumn(Context context, Uri uri, String selection,
                                   String[] selectionArgs) {
    Cursor cursor = null;
    final String column = "_data";
    final String[] projection = {
            column
    };

    try {
        cursor = context.getContentResolver().query(uri, projection, selection, selectionArgs,
                null);
        if (cursor != null && cursor.moveToFirst()) {
            final int column_index = cursor.getColumnIndexOrThrow(column);
            return cursor.getString(column_index);
        }
    }
    finally {
        if (cursor != null)
            cursor.close();
    }
    return null;
}

Where is the IIS Express configuration / metabase file found?

To come full circle and include all versions of Visual Studio, @Myster originally stated that;

Pre Visual Studio 2015 the paths to applicationhost.config were:

%userprofile%\documents\iisexpress\config\applicationhost.config
%userprofile%\my documents\iisexpress\config\applicationhost.config

Visual Studio 2015/2017 path can be found at: (credit: @Talon)

$(solutionDir)\.vs\config\applicationhost.config

Visual Studio 2019 path can be found at: (credit: @Talon)

$(solutionDir)\.vs\config\$(ProjectName)\applicationhost.config

But the part that might get some people is that the project settings in the .sln file can repopulate the applicationhost.config for Visual Studio 2015+. (credit: @Lex Li)

So, if you make a change in the applicationhost.config you also have to make sure your changes match here:

$(solutionDir)\ProjectName.sln

The two important settings should look like:

Project("{XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX}") = "ProjectName", "ProjectPath\", "{XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX}"

and

VWDPort = "Port#"

What is important here is that the two settings in the .sln must match the name and bindingInformation respectively in the applicationhost.config file if you plan on making changes. There may be more places that link these two files and I will update as I find more links either by comments or more experience.

REST API using POST instead of GET

If I understand the question correctly, he needs to perform a REST GET action, but wonders if it's OK to send in data via HTTP POST method.

As Scott had nicely laid out in his answer earlier, there are many good reasons to POST input data. IMHO it should be done this way, if quality of solution is the top priority.

A while back we created an REST API to authenticate users, taking username/password and returning an access token. The API is encrypted under TLS, but exposed to public internet. After evaluating different options, we chose HTTP POST for the REST method of "GET access token," because that's the only way to meet security standards.

Docker: unable to prepare context: unable to evaluate symlinks in Dockerfile path: GetFileAttributesEx

In Linux, folders are case sensitive. I was getting this error because folder name TestAPI and was putting TestApi.

How to remove new line characters from data rows in mysql?

Removes trailing returns when importing from Excel. When you execute this, you may receive an error that there is no WHERE; ignore and execute.

UPDATE table_name SET col_name = TRIM(TRAILING '\r' FROM col_name)

How to format a Date in MM/dd/yyyy HH:mm:ss format in JavaScript?

You can always format a date by extracting the parts and combine them using string functions:

_x000D_
_x000D_
var date = new Date();_x000D_
var dateStr =_x000D_
  ("00" + (date.getMonth() + 1)).slice(-2) + "/" +_x000D_
  ("00" + date.getDate()).slice(-2) + "/" +_x000D_
  date.getFullYear() + " " +_x000D_
  ("00" + date.getHours()).slice(-2) + ":" +_x000D_
  ("00" + date.getMinutes()).slice(-2) + ":" +_x000D_
  ("00" + date.getSeconds()).slice(-2);_x000D_
console.log(dateStr);
_x000D_
_x000D_
_x000D_

Symfony2 Setting a default choice field selection

You can use "preferred_choices" and "push" the name you want to select to the top of the list. Then it will be selected by default.

'preferred_choices' => array(1), //1 is item number

entity Field Type

How to search and replace text in a file?

With a single with block, you can search and replace your text:

with open('file.txt','r+') as f:
    filedata = f.read()
    filedata = filedata.replace('abc','xyz')
    f.truncate(0)
    f.write(filedata)

"unmappable character for encoding" warning in Java

Most of the time this compile error comes when unicode(UTF-8 encoded) file compiling

javac -encoding UTF-8 HelloWorld.java

and also You can add this compile option to your IDE ex: Intellij idea
(File>settings>Java Compiler) add as additional command line parameter

enter image description here

-encoding : encoding Set the source file encoding name, such as EUC-JP and UTF-8.. If -encoding is not specified, the platform default converter is used. (DOC)

Safely turning a JSON string into an object

JSON.parse(jsonString) is a pure JavaScript approach so long as you can guarantee a reasonably modern browser.

App.Config Transformation for projects which are not Web Projects in Visual Studio?

I wrote nice extension to automate app.config transformation like the one built in Web Application Project Configuration Transform

The biggest advantage of this extension is that you don’t need to install it on all build machines

how to download image from any web page in java

   // Do you want to download an image?
   // But are u denied access?
   // well here is the solution.

    public static void DownloadImage(String search, String path) {

    // This will get input data from the server
    InputStream inputStream = null;

    // This will read the data from the server;
    OutputStream outputStream = null;

    try {
        // This will open a socket from client to server
        URL url = new URL(search);

       // This user agent is for if the server wants real humans to visit
        String USER_AGENT = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.87 Safari/537.36";

       // This socket type will allow to set user_agent
        URLConnection con = url.openConnection();

        // Setting the user agent
        con.setRequestProperty("User-Agent", USER_AGENT);

        // Requesting input data from server
        inputStream = con.getInputStream();

        // Open local file writer
        outputStream = new FileOutputStream(path);

        // Limiting byte written to file per loop
        byte[] buffer = new byte[2048];

        // Increments file size
        int length;

        // Looping until server finishes
        while ((length = inputStream.read(buffer)) != -1) {
            // Writing data
            outputStream.write(buffer, 0, length);
        }
    } catch (Exception ex) {
        Logger.getLogger(WebCrawler.class.getName()).log(Level.SEVERE, null, ex);
     }

     // closing used resources
     // The computer will not be able to use the image
     // This is a must

     outputStream.close();
     inputStream.close();
}

'if' statement in jinja2 template

We need to remember that the {% endif %} comes after the {% else %}.

So this is an example:

{% if someTest %}
     <p> Something is True </p>
{% else %}
     <p> Something is False </p>
{% endif %}

SQL SELECT WHERE field contains words

SELECT * FROM MyTable WHERE Column1 Like "*word*"

This will display all the records where column1 has a partial value contains word.

vi/vim editor, copy a block (not usual action)

Keyboard shortcuts to that are:

  1. For copy: Place cursor on starting of block and press md and then goto end of block and press y'd. This will select the block to paste it press p

  2. For cut: Place cursor on starting of block and press ma and then goto end of block and press d'a. This will select the block to paste it press p

How to pass parameters to the DbContext.Database.ExecuteSqlCommand method?

Simplified version for Oracle. If you don't want to create OracleParameter

var sql = "Update [User] SET FirstName = :p0 WHERE Id = :p1";
context.Database.ExecuteSqlCommand(sql, firstName, id);

how to create a cookie and add to http response from inside my service layer?

To add a new cookie, use HttpServletResponse.addCookie(Cookie). The Cookie is pretty much a key value pair taking a name and value as strings on construction.

SQL Query with Join, Count and Where

You have to use GROUP BY so you will have multiple records returned,

SELECT  COUNT(*) TotalCount, 
        b.category_id, 
        b.category_name 
FROM    table1 a
        INNER JOIN table2 b
            ON a.category_id = b.category_id 
WHERE   a.colour <> 'red'
GROUP   BY b.category_id, b.category_name

Passing variables in remote ssh command

The list of accepted environment variables on SSHD by default includes LC_*. Thus:

LC_MY_BUILDN="1.2.3" ssh -o "SendEnv LC_MY_BUILDN" ssh-host 'echo $LC_MY_BUILDN'
1.2.3

What does %>% function mean in R?

%...% operators

%>% has no builtin meaning but the user (or a package) is free to define operators of the form %whatever% in any way they like. For example, this function will return a string consisting of its left argument followed by a comma and space and then it's right argument.

"%,%" <- function(x, y) paste0(x, ", ", y)

# test run

"Hello" %,% "World"
## [1] "Hello, World"

The base of R provides %*% (matrix mulitiplication), %/% (integer division), %in% (is lhs a component of the rhs?), %o% (outer product) and %x% (kronecker product). It is not clear whether %% falls in this category or not but it represents modulo.

expm The R package, expm, defines a matrix power operator %^%. For an example see Matrix power in R .

operators The operators R package has defined a large number of such operators such as %!in% (for not %in%). See http://cran.r-project.org/web/packages/operators/operators.pdf

igraph This package defines %--% , %->% and %<-% to select edges.

lubridate This package defines %m+% and %m-% to add and subtract months and %--% to define an interval. igraph also defines %--% .

Pipes

magrittr In the case of %>% the magrittr R package has defined it as discussed in the magrittr vignette. See http://cran.r-project.org/web/packages/magrittr/vignettes/magrittr.html

magittr has also defined a number of other such operators too. See the Additional Pipe Operators section of the prior link which discusses %T>%, %<>% and %$% and http://cran.r-project.org/web/packages/magrittr/magrittr.pdf for even more details.

dplyr The dplyr R package used to define a %.% operator which is similar; however, it has been deprecated and dplyr now recommends that users use %>% which dplyr imports from magrittr and makes available to the dplyr user. As David Arenburg has mentioned in the comments this SO question discusses the differences between it and magrittr's %>% : Differences between %.% (dplyr) and %>% (magrittr)

pipeR The R package, pipeR, defines a %>>% operator that is similar to magrittr's %>% and can be used as an alternative to it. See http://renkun.me/pipeR-tutorial/

The pipeR package also has defined a number of other such operators too. See: http://cran.r-project.org/web/packages/pipeR/pipeR.pdf

postlogic The postlogic package defined %if% and %unless% operators.

wrapr The R package, wrapr, defines a dot pipe %.>% that is an explicit version of %>% in that it does not do implicit insertion of arguments but only substitutes explicit uses of dot on the right hand side. This can be considered as another alternative to %>%. See https://winvector.github.io/wrapr/articles/dot_pipe.html

Bizarro pipe. This is not really a pipe but rather some clever base syntax to work in a way similar to pipes without actually using pipes. It is discussed in http://www.win-vector.com/blog/2017/01/using-the-bizarro-pipe-to-debug-magrittr-pipelines-in-r/ The idea is that instead of writing:

1:8 %>% sum %>% sqrt
## [1] 6

one writes the following. In this case we explicitly use dot rather than eliding the dot argument and end each component of the pipeline with an assignment to the variable whose name is dot (.) . We follow that with a semicolon.

1:8 ->.; sum(.) ->.; sqrt(.)
## [1] 6

Update Added info on expm package and simplified example at top. Added postlogic package.

How to list all users in a Linux group?

just a little grep and tr:

$ grep ^$GROUP /etc/group | grep -o '[^:]*$' | tr ',' '\n'
user1
user2
user3

How to write a function that takes a positive integer N and returns a list of the first N natural numbers

Do I even need a for loop to create a list?

No, you can (and in general circumstances should) use the built-in function range():

>>> range(1,5)
[1, 2, 3, 4]

i.e.

def naturalNumbers(n):
    return range(1, n + 1)

Python 3's range() is slightly different in that it returns a range object and not a list, so if you're using 3.x wrap it all in list(): list(range(1, n + 1)).

Best way to select random rows PostgreSQL

You can examine and compare the execution plan of both by using

EXPLAIN select * from table where random() < 0.01;
EXPLAIN select * from table order by random() limit 1000;

A quick test on a large table1 shows, that the ORDER BY first sorts the complete table and then picks the first 1000 items. Sorting a large table not only reads that table but also involves reading and writing temporary files. The where random() < 0.1 only scans the complete table once.

For large tables this might not what you want as even one complete table scan might take to long.

A third proposal would be

select * from table where random() < 0.01 limit 1000;

This one stops the table scan as soon as 1000 rows have been found and therefore returns sooner. Of course this bogs down the randomness a bit, but perhaps this is good enough in your case.

Edit: Besides of this considerations, you might check out the already asked questions for this. Using the query [postgresql] random returns quite a few hits.

And a linked article of depez outlining several more approaches:


1 "large" as in "the complete table will not fit into the memory".

How to Update a Component without refreshing full page - Angular

To refresh the component at regular intervals I found this the best method. In the ngOnInit method setTimeOut function

ngOnInit(): void {
  setTimeout(() => { this.ngOnInit() }, 1000 * 10)
}
//10 is the number of seconds

How to add bootstrap to an angular-cli project

  1. Install bootstrap

    npm install bootstrap@next
    
  2. Add code to .angular-cli.json:

    "styles": [
      "styles.css",
      "../node_modules/bootstrap/dist/css/bootstrap.css"
    ],
    "scripts": [
      "../node_modules/jquery/dist/jquery.js",
      "../node_modules/tether/dist/js/tether.js",
      "../node_modules/bootstrap/dist/js/bootstrap.js"
    ],
    
  3. Last add bootstrap.css to your code style.scss

    @import "../node_modules/bootstrap/dist/css/bootstrap.min.css";
    
  4. Restart your local server

Node.js Web Application examples/tutorials

I would suggest you check out the various tutorials that are coming out lately. My current fav is:

http://nodetuts.com/

Hope this helps.

How to cast or convert an unsigned int to int in C?

IMHO this question is an evergreen. As stated in various answers, the assignment of an unsigned value that is not in the range [0,INT_MAX] is implementation defined and might even raise a signal. If the unsigned value is considered to be a two's complement representation of a signed number, the probably most portable way is IMHO the way shown in the following code snippet:

#include <limits.h>
unsigned int u;
int i;

if (u <= (unsigned int)INT_MAX)
  i = (int)u; /*(1)*/
else if (u >= (unsigned int)INT_MIN)
  i = -(int)~u - 1; /*(2)*/
else
  i = INT_MIN; /*(3)*/
  • Branch (1) is obvious and cannot invoke overflow or traps, since it is value-preserving.

  • Branch (2) goes through some pains to avoid signed integer overflow by taking the one's complement of the value by bit-wise NOT, casts it to 'int' (which cannot overflow now), negates the value and subtracts one, which can also not overflow here.

  • Branch (3) provides the poison we have to take on one's complement or sign/magnitude targets, because the signed integer representation range is smaller than the two's complement representation range.

This is likely to boil down to a simple move on a two's complement target; at least I've observed such with GCC and CLANG. Also branch (3) is unreachable on such a target -- if one wants to limit the execution to two's complement targets, the code could be condensed to

#include <limits.h>
unsigned int u;
int i;

if (u <= (unsigned int)INT_MAX)
  i = (int)u; /*(1)*/
else
  i = -(int)~u - 1; /*(2)*/

The recipe works with any signed/unsigned type pair, and the code is best put into a macro or inline function so the compiler/optimizer can sort it out. (In which case rewriting the recipe with a ternary operator is helpful. But it's less readable and therefore not a good way to explain the strategy.)

And yes, some of the casts to 'unsigned int' are redundant, but

  • they might help the casual reader

  • some compilers issue warnings on signed/unsigned compares, because the implicit cast causes some non-intuitive behavior by language design

Regular expression to match URLs in Java

This works too:

String regex = "\\b(https?|ftp|file)://[-a-zA-Z0-9+&@#/%?=~_|!:,.;]*[-a-zA-Z0-9+&@#/%=~_|]";

Note:

String regex = "<\\b(https?|ftp|file)://[-a-zA-Z0-9+&@#/%?=~_|!:,.;]*[-a-zA-Z0-9+&@#/%=~_|]>"; // matches <http://google.com>

String regex = "<^(https?|ftp|file)://[-a-zA-Z0-9+&@#/%?=~_|!:,.;]*[-a-zA-Z0-9+&@#/%=~_|]>"; // does not match <http://google.com>

So probably the first one is more useful for general use.

How to access the GET parameters after "?" in Express?

The express manual says that you should use req.query to access the QueryString.

// Requesting /display/post?size=small
app.get('/display/post', function(req, res, next) {

  var isSmall = req.query.size === 'small'; // > true
  // ...

});

Comparing two maps

As long as you override equals() on each key and value contained in the map, then m1.equals(m2) should be reliable to check for maps equality.

The same result can be obtained also by comparing toString() of each map as you suggested, but using equals() is a more intuitive approach.

May not be your specific situation, but if you store arrays in the map, may be a little tricky, because they must be compared value by value, or using Arrays.equals(). More details about this see here.

How can I disable all views inside the layout?

Although not quite the same as disabling views within a layout, it is worth mentioning that you can prevent all children from receiving touches (without having to recurse the layout hierarchy) by overriding the ViewGroup#onInterceptTouchEvent(MotionEvent) method:

public class InterceptTouchEventFrameLayout extends FrameLayout {

    private boolean interceptTouchEvents;

    // ...

    public void setInterceptTouchEvents(boolean interceptTouchEvents) {
        this.interceptTouchEvents = interceptTouchEvents;
    }

    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev) {
        return interceptTouchEvents || super.onInterceptTouchEvent(ev);
    }

}

Then you can prevent children from receiving touch events:

InterceptTouchEventFrameLayout layout = (InterceptTouchEventFrameLayout) findViewById(R.id.layout);
layout.setInterceptTouchEvents(true);

If you have a click listener set on layout, it will still be triggered.

How to solve “Microsoft Visual Studio (VS)” error “Unable to connect to the configured development Web server”

I am using visual studio 2015. Deleting .vs folder in the project folder helped me to fix this. You must close the visual studio first.

Git vs Team Foundation Server

I think, the statement

everyone hates it except me

makes any further discussion waste: when you keep using Git, they will blame you if anything goes wrong.

Apart from this, for me Git has two advantages over a centralized VCS that I appreciate most (as partly described by Rob Sobers):

  • automatic backup of the whole repo: everytime someone pulls from the central repo, he/she gets a full history of the changes. When one repo gets lost: don't worry, take one of those present on every workstation.
  • offline repo access: when I'm working at home (or in an airplane or train), I can see the full history of the project, every single checkin, without starting up my VPN connection to work and can work like I were at work: checkin, checkout, branch, anything.

But as I said: I think that you're fighting a lost battle: when everyone hates Git, don't use Git. It could help you more to know why they hate Git instead of trying them to convince them.

If they simply don't want it 'cause it's new to them and are not willing to learn something new: are you sure that you will do successful development with that staff?

Does really every single person hate Git or are they influenced by some opinion leaders? Find the leaders and ask them what's the problem. Convince them and you'll convince the rest of the team.

If you cannot convince the leaders: forget about using Git, take the TFS. Will make your life easier.

How to push objects in AngularJS between ngRepeat arrays

Try this one also...

_x000D_
_x000D_
<!DOCTYPE html>_x000D_
<html>_x000D_
_x000D_
<body>_x000D_
_x000D_
  <p>Click the button to join two arrays.</p>_x000D_
_x000D_
  <button onclick="myFunction()">Try it</button>_x000D_
_x000D_
  <p id="demo"></p>_x000D_
  <p id="demo1"></p>_x000D_
  <script>_x000D_
    function myFunction() {_x000D_
      var hege = [{_x000D_
        1: "Cecilie",_x000D_
        2: "Lone"_x000D_
      }];_x000D_
      var stale = [{_x000D_
        1: "Emil",_x000D_
        2: "Tobias"_x000D_
      }];_x000D_
      var hege = hege.concat(stale);_x000D_
      document.getElementById("demo1").innerHTML = hege;_x000D_
      document.getElementById("demo").innerHTML = stale;_x000D_
    }_x000D_
  </script>_x000D_
_x000D_
</body>_x000D_
_x000D_
</html>
_x000D_
_x000D_
_x000D_

PHP: Get key from array?

Try this

foreach(array_keys($array) as $nmkey)
    {
        echo $nmkey;
    }

How do I install imagemagick with homebrew?

Answering old thread here (and a bit off-topic) because it's what I found when I was searching how to install Image Magick on Mac OS to run on the local webserver. It's not enough to brew install Imagemagick. You have to also PECL install it so the PHP module is loaded.

From this SO answer:

brew install php
brew install imagemagick
brew install pkg-config
pecl install imagick

And you may need to sudo apachectl restart. Then check your phpinfo() within a simple php script running on your web server.

If it's still not there, you probably have an issue with running multiple versions of PHP on the same Mac (one through the command line, one through your web server). It's beyond the scope of this answer to resolve that issue, but there are some good options out there.

Best way to check function arguments?

In this elongated answer, we implement a Python 3.x-specific type checking decorator based on PEP 484-style type hints in less than 275 lines of pure-Python (most of which is explanatory docstrings and comments) – heavily optimized for industrial-strength real-world use complete with a py.test-driven test suite exercising all possible edge cases.

Feast on the unexpected awesome of bear typing:

>>> @beartype
... def spirit_bear(kermode: str, gitgaata: (str, int)) -> tuple:
...     return (kermode, gitgaata, "Moksgm'ol", 'Ursus americanus kermodei')
>>> spirit_bear(0xdeadbeef, 'People of the Cane')
AssertionError: parameter kermode=0xdeadbeef not of <class "str">

As this example suggests, bear typing explicitly supports type checking of parameters and return values annotated as either simple types or tuples of such types. Golly!

O.K., that's actually unimpressive. @beartype resembles every other Python 3.x-specific type checking decorator based on PEP 484-style type hints in less than 275 lines of pure-Python. So what's the rub, bub?

Pure Bruteforce Hardcore Efficiency

Bear typing is dramatically more efficient in both space and time than all existing implementations of type checking in Python to the best of my limited domain knowledge. (More on that later.)

Efficiency usually doesn't matter in Python, however. If it did, you wouldn't be using Python. Does type checking actually deviate from the well-established norm of avoiding premature optimization in Python? Yes. Yes, it does.

Consider profiling, which adds unavoidable overhead to each profiled metric of interest (e.g., function calls, lines). To ensure accurate results, this overhead is mitigated by leveraging optimized C extensions (e.g., the _lsprof C extension leveraged by the cProfile module) rather than unoptimized pure-Python (e.g., the profile module). Efficiency really does matter when profiling.

Type checking is no different. Type checking adds overhead to each function call type checked by your application – ideally, all of them. To prevent well-meaning (but sadly small-minded) coworkers from removing the type checking you silently added after last Friday's caffeine-addled allnighter to your geriatric legacy Django web app, type checking must be fast. So fast that no one notices it's there when you add it without telling anyone. I do this all the time! Stop reading this if you are a coworker.

If even ludicrous speed isn't enough for your gluttonous application, however, bear typing may be globally disabled by enabling Python optimizations (e.g., by passing the -O option to the Python interpreter):

$ python3 -O
# This succeeds only when type checking is optimized away. See above!
>>> spirit_bear(0xdeadbeef, 'People of the Cane')
(0xdeadbeef, 'People of the Cane', "Moksgm'ol", 'Ursus americanus kermodei')

Just because. Welcome to bear typing.

What The...? Why "bear"? You're a Neckbeard, Right?

Bear typing is bare-metal type checking – that is, type checking as close to the manual approach of type checking in Python as feasible. Bear typing is intended to impose no performance penalties, compatibility constraints, or third-party dependencies (over and above that imposed by the manual approach, anyway). Bear typing may be seamlessly integrated into existing codebases and test suites without modification.

Everyone's probably familiar with the manual approach. You manually assert each parameter passed to and/or return value returned from every function in your codebase. What boilerplate could be simpler or more banal? We've all seen it a hundred times a googleplex times, and vomited a little in our mouths everytime we did. Repetition gets old fast. DRY, yo.

Get your vomit bags ready. For brevity, let's assume a simplified easy_spirit_bear() function accepting only a single str parameter. Here's what the manual approach looks like:

def easy_spirit_bear(kermode: str) -> str:
    assert isinstance(kermode, str), 'easy_spirit_bear() parameter kermode={} not of <class "str">'.format(kermode)
    return_value = (kermode, "Moksgm'ol", 'Ursus americanus kermodei')
    assert isinstance(return_value, str), 'easy_spirit_bear() return value {} not of <class "str">'.format(return_value)
    return return_value

Python 101, right? Many of us passed that class.

Bear typing extracts the type checking manually performed by the above approach into a dynamically defined wrapper function automatically performing the same checks – with the added benefit of raising granular TypeError rather than ambiguous AssertionError exceptions. Here's what the automated approach looks like:

def easy_spirit_bear_wrapper(*args, __beartype_func=easy_spirit_bear, **kwargs):
    if not (
        isinstance(args[0], __beartype_func.__annotations__['kermode'])
        if 0 < len(args) else
        isinstance(kwargs['kermode'], __beartype_func.__annotations__['kermode'])
        if 'kermode' in kwargs else True):
            raise TypeError(
                'easy_spirit_bear() parameter kermode={} not of {!r}'.format(
                args[0] if 0 < len(args) else kwargs['kermode'],
                __beartype_func.__annotations__['kermode']))

    return_value = __beartype_func(*args, **kwargs)

    if not isinstance(return_value, __beartype_func.__annotations__['return']):
        raise TypeError(
            'easy_spirit_bear() return value {} not of {!r}'.format(
                return_value, __beartype_func.__annotations__['return']))

    return return_value

It's long-winded. But it's also basically* as fast as the manual approach. * Squinting suggested.

Note the complete lack of function inspection or iteration in the wrapper function, which contains a similar number of tests as the original function – albeit with the additional (maybe negligible) costs of testing whether and how the parameters to be type checked are passed to the current function call. You can't win every battle.

Can such wrapper functions actually be reliably generated to type check arbitrary functions in less than 275 lines of pure Python? Snake Plisskin says, "True story. Got a smoke?"

And, yes. I may have a neckbeard.

No, Srsly. Why "bear"?

Bear beats duck. Duck may fly, but bear may throw salmon at duck. In Canada, nature can surprise you.

Next question.

What's So Hot about Bears, Anyway?

Existing solutions do not perform bare-metal type checking – at least, none I've grepped across. They all iteratively reinspect the signature of the type-checked function on each function call. While negligible for a single call, reinspection overhead is usually non-negligible when aggregated over all calls. Really, really non-negligible.

It's not simply efficiency concerns, however. Existing solutions also often fail to account for common edge cases. This includes most if not all toy decorators provided as stackoverflow answers here and elsewhere. Classic failures include:

  • Failing to type check keyword arguments and/or return values (e.g., sweeneyrod's @checkargs decorator).
  • Failing to support tuples (i.e., unions) of types accepted by the isinstance() builtin.
  • Failing to propagate the name, docstring, and other identifying metadata from the original function onto the wrapper function.
  • Failing to supply at least a semblance of unit tests. (Kind of critical.)
  • Raising generic AssertionError exceptions rather than specific TypeError exceptions on failed type checks. For granularity and sanity, type checking should never raise generic exceptions.

Bear typing succeeds where non-bears fail. All one, all bear!

Bear Typing Unbared

Bear typing shifts the space and time costs of inspecting function signatures from function call time to function definition time – that is, from the wrapper function returned by the @beartype decorator into the decorator itself. Since the decorator is only called once per function definition, this optimization yields glee for all.

Bear typing is an attempt to have your type checking cake and eat it, too. To do so, @beartype:

  1. Inspects the signature and annotations of the original function.
  2. Dynamically constructs the body of the wrapper function type checking the original function. Thaaat's right. Python code generating Python code.
  3. Dynamically declares this wrapper function via the exec() builtin.
  4. Returns this wrapper function.

Shall we? Let's dive into the deep end.

# If the active Python interpreter is *NOT* optimized (e.g., option "-O" was
# *NOT* passed to this interpreter), enable type checking.
if __debug__:
    import inspect
    from functools import wraps
    from inspect import Parameter, Signature

    def beartype(func: callable) -> callable:
        '''
        Decorate the passed **callable** (e.g., function, method) to validate
        both all annotated parameters passed to this callable _and_ the
        annotated value returned by this callable if any.

        This decorator performs rudimentary type checking based on Python 3.x
        function annotations, as officially documented by PEP 484 ("Type
        Hints"). While PEP 484 supports arbitrarily complex type composition,
        this decorator requires _all_ parameter and return value annotations to
        be either:

        * Classes (e.g., `int`, `OrderedDict`).
        * Tuples of classes (e.g., `(int, OrderedDict)`).

        If optimizations are enabled by the active Python interpreter (e.g., due
        to option `-O` passed to this interpreter), this decorator is a noop.

        Raises
        ----------
        NameError
            If any parameter has the reserved name `__beartype_func`.
        TypeError
            If either:
            * Any parameter or return value annotation is neither:
              * A type.
              * A tuple of types.
            * The kind of any parameter is unrecognized. This should _never_
              happen, assuming no significant changes to Python semantics.
        '''

        # Raw string of Python statements comprising the body of this wrapper,
        # including (in order):
        #
        # * A "@wraps" decorator propagating the name, docstring, and other
        #   identifying metadata of the original function to this wrapper.
        # * A private "__beartype_func" parameter initialized to this function.
        #   In theory, the "func" parameter passed to this decorator should be
        #   accessible as a closure-style local in this wrapper. For unknown
        #   reasons (presumably, a subtle bug in the exec() builtin), this is
        #   not the case. Instead, a closure-style local must be simulated by
        #   passing the "func" parameter to this function at function
        #   definition time as the default value of an arbitrary parameter. To
        #   ensure this default is *NOT* overwritten by a function accepting a
        #   parameter of the same name, this edge case is tested for below.
        # * Assert statements type checking parameters passed to this callable.
        # * A call to this callable.
        # * An assert statement type checking the value returned by this
        #   callable.
        #
        # While there exist numerous alternatives (e.g., appending to a list or
        # bytearray before joining the elements of that iterable into a string),
        # these alternatives are either slower (as in the case of a list, due to
        # the high up-front cost of list construction) or substantially more
        # cumbersome (as in the case of a bytearray). Since string concatenation
        # is heavily optimized by the official CPython interpreter, the simplest
        # approach is (curiously) the most ideal.
        func_body = '''
@wraps(__beartype_func)
def func_beartyped(*args, __beartype_func=__beartype_func, **kwargs):
'''

        # "inspect.Signature" instance encapsulating this callable's signature.
        func_sig = inspect.signature(func)

        # Human-readable name of this function for use in exceptions.
        func_name = func.__name__ + '()'

        # For the name of each parameter passed to this callable and the
        # "inspect.Parameter" instance encapsulating this parameter (in the
        # passed order)...
        for func_arg_index, func_arg in enumerate(func_sig.parameters.values()):
            # If this callable redefines a parameter initialized to a default
            # value by this wrapper, raise an exception. Permitting this
            # unlikely edge case would permit unsuspecting users to
            # "accidentally" override these defaults.
            if func_arg.name == '__beartype_func':
                raise NameError(
                    'Parameter {} reserved for use by @beartype.'.format(
                        func_arg.name))

            # If this parameter is both annotated and non-ignorable for purposes
            # of type checking, type check this parameter.
            if (func_arg.annotation is not Parameter.empty and
                func_arg.kind not in _PARAMETER_KIND_IGNORED):
                # Validate this annotation.
                _check_type_annotation(
                    annotation=func_arg.annotation,
                    label='{} parameter {} type'.format(
                        func_name, func_arg.name))

                # String evaluating to this parameter's annotated type.
                func_arg_type_expr = (
                    '__beartype_func.__annotations__[{!r}]'.format(
                        func_arg.name))

                # String evaluating to this parameter's current value when
                # passed as a keyword.
                func_arg_value_key_expr = 'kwargs[{!r}]'.format(func_arg.name)

                # If this parameter is keyword-only, type check this parameter
                # only by lookup in the variadic "**kwargs" dictionary.
                if func_arg.kind is Parameter.KEYWORD_ONLY:
                    func_body += '''
    if {arg_name!r} in kwargs and not isinstance(
        {arg_value_key_expr}, {arg_type_expr}):
        raise TypeError(
            '{func_name} keyword-only parameter '
            '{arg_name}={{}} not a {{!r}}'.format(
                {arg_value_key_expr}, {arg_type_expr}))
'''.format(
                        func_name=func_name,
                        arg_name=func_arg.name,
                        arg_type_expr=func_arg_type_expr,
                        arg_value_key_expr=func_arg_value_key_expr,
                    )
                # Else, this parameter may be passed either positionally or as
                # a keyword. Type check this parameter both by lookup in the
                # variadic "**kwargs" dictionary *AND* by index into the
                # variadic "*args" tuple.
                else:
                    # String evaluating to this parameter's current value when
                    # passed positionally.
                    func_arg_value_pos_expr = 'args[{!r}]'.format(
                        func_arg_index)

                    func_body += '''
    if not (
        isinstance({arg_value_pos_expr}, {arg_type_expr})
        if {arg_index} < len(args) else
        isinstance({arg_value_key_expr}, {arg_type_expr})
        if {arg_name!r} in kwargs else True):
            raise TypeError(
                '{func_name} parameter {arg_name}={{}} not of {{!r}}'.format(
                {arg_value_pos_expr} if {arg_index} < len(args) else {arg_value_key_expr},
                {arg_type_expr}))
'''.format(
                    func_name=func_name,
                    arg_name=func_arg.name,
                    arg_index=func_arg_index,
                    arg_type_expr=func_arg_type_expr,
                    arg_value_key_expr=func_arg_value_key_expr,
                    arg_value_pos_expr=func_arg_value_pos_expr,
                )

        # If this callable's return value is both annotated and non-ignorable
        # for purposes of type checking, type check this value.
        if func_sig.return_annotation not in _RETURN_ANNOTATION_IGNORED:
            # Validate this annotation.
            _check_type_annotation(
                annotation=func_sig.return_annotation,
                label='{} return type'.format(func_name))

            # Strings evaluating to this parameter's annotated type and
            # currently passed value, as above.
            func_return_type_expr = (
                "__beartype_func.__annotations__['return']")

            # Call this callable, type check the returned value, and return this
            # value from this wrapper.
            func_body += '''
    return_value = __beartype_func(*args, **kwargs)
    if not isinstance(return_value, {return_type}):
        raise TypeError(
            '{func_name} return value {{}} not of {{!r}}'.format(
                return_value, {return_type}))
    return return_value
'''.format(func_name=func_name, return_type=func_return_type_expr)
        # Else, call this callable and return this value from this wrapper.
        else:
            func_body += '''
    return __beartype_func(*args, **kwargs)
'''

        # Dictionary mapping from local attribute name to value. For efficiency,
        # only those local attributes explicitly required in the body of this
        # wrapper are copied from the current namespace. (See below.)
        local_attrs = {'__beartype_func': func}

        # Dynamically define this wrapper as a closure of this decorator. For
        # obscure and presumably uninteresting reasons, Python fails to locally
        # declare this closure when the locals() dictionary is passed; to
        # capture this closure, a local dictionary must be passed instead.
        exec(func_body, globals(), local_attrs)

        # Return this wrapper.
        return local_attrs['func_beartyped']

    _PARAMETER_KIND_IGNORED = {
        Parameter.POSITIONAL_ONLY, Parameter.VAR_POSITIONAL, Parameter.VAR_KEYWORD,
    }
    '''
    Set of all `inspect.Parameter.kind` constants to be ignored during
    annotation- based type checking in the `@beartype` decorator.

    This includes:

    * Constants specific to variadic parameters (e.g., `*args`, `**kwargs`).
      Variadic parameters cannot be annotated and hence cannot be type checked.
    * Constants specific to positional-only parameters, which apply to non-pure-
      Python callables (e.g., defined by C extensions). The `@beartype`
      decorator applies _only_ to pure-Python callables, which provide no
      syntactic means of specifying positional-only parameters.
    '''

    _RETURN_ANNOTATION_IGNORED = {Signature.empty, None}
    '''
    Set of all annotations for return values to be ignored during annotation-
    based type checking in the `@beartype` decorator.

    This includes:

    * `Signature.empty`, signifying a callable whose return value is _not_
      annotated.
    * `None`, signifying a callable returning no value. By convention, callables
      returning no value are typically annotated to return `None`. Technically,
      callables whose return values are annotated as `None` _could_ be
      explicitly checked to return `None` rather than a none-`None` value. Since
      return values are safely ignorable by callers, however, there appears to
      be little real-world utility in enforcing this constraint.
    '''

    def _check_type_annotation(annotation: object, label: str) -> None:
        '''
        Validate the passed annotation to be a valid type supported by the
        `@beartype` decorator.

        Parameters
        ----------
        annotation : object
            Annotation to be validated.
        label : str
            Human-readable label describing this annotation, interpolated into
            exceptions raised by this function.

        Raises
        ----------
        TypeError
            If this annotation is neither a new-style class nor a tuple of
            new-style classes.
        '''

        # If this annotation is a tuple, raise an exception if any member of
        # this tuple is not a new-style class. Note that the "__name__"
        # attribute tested below is not defined by old-style classes and hence
        # serves as a helpful means of identifying new-style classes.
        if isinstance(annotation, tuple):
            for member in annotation:
                if not (
                    isinstance(member, type) and hasattr(member, '__name__')):
                    raise TypeError(
                        '{} tuple member {} not a new-style class'.format(
                            label, member))
        # Else if this annotation is not a new-style class, raise an exception.
        elif not (
            isinstance(annotation, type) and hasattr(annotation, '__name__')):
            raise TypeError(
                '{} {} neither a new-style class nor '
                'tuple of such classes'.format(label, annotation))

# Else, the active Python interpreter is optimized. In this case, disable type
# checking by reducing this decorator to the identity decorator.
else:
    def beartype(func: callable) -> callable:
        return func

And leycec said, Let the @beartype bring forth type checking fastly: and it was so.

Caveats, Curses, and Empty Promises

Nothing is perfect. Even bear typing.

Caveat I: Default Values Unchecked

Bear typing does not type check unpassed parameters assigned default values. In theory, it could. But not in 275 lines or less and certainly not as a stackoverflow answer.

The safe (...probably totally unsafe) assumption is that function implementers claim they knew what they were doing when they defined default values. Since default values are typically constants (...they'd better be!), rechecking the types of constants that never change on each function call assigned one or more default values would contravene the fundamental tenet of bear typing: "Don't repeat yourself over and oooover and oooo-oooover again."

Show me wrong and I will shower you with upvotes.

Caveat II: No PEP 484

PEP 484 ("Type Hints") formalized the use of function annotations first introduced by PEP 3107 ("Function Annotations"). Python 3.5 superficially supports this formalization with a new top-level typing module, a standard API for composing arbitrarily complex types from simpler types (e.g., Callable[[Arg1Type, Arg2Type], ReturnType], a type describing a function accepting two arguments of type Arg1Type and Arg2Type and returning a value of type ReturnType).

Bear typing supports none of them. In theory, it could. But not in 275 lines or less and certainly not as a stackoverflow answer.

Bear typing does, however, support unions of types in the same way that the isinstance() builtin supports unions of types: as tuples. This superficially corresponds to the typing.Union type – with the obvious caveat that typing.Union supports arbitrarily complex types, while tuples accepted by @beartype support only simple classes. In my defense, 275 lines.

Tests or It Didn't Happen

Here's the gist of it. Get it, gist? I'll stop now.

As with the @beartype decorator itself, these py.test tests may be seamlessly integrated into existing test suites without modification. Precious, isn't it?

Now the mandatory neckbeard rant nobody asked for.

A History of API Violence

Python 3.5 provides no actual support for using PEP 484 types. wat?

It's true: no type checking, no type inference, no type nuthin'. Instead, developers are expected to routinely run their entire codebases through heavyweight third-party CPython interpreter wrappers implementing a facsimile of such support (e.g., mypy). Of course, these wrappers impose:

  • A compatibility penalty. As the official mypy FAQ admits in response to the frequently asked question "Can I use mypy to type check my existing Python code?": "It depends. Compatibility is pretty good, but some Python features are not yet implemented or fully supported." A subsequent FAQ response clarifies this incompatibility by stating that:
    • "...your code must make attributes explicit and use a explicit protocol representation." Grammar police see your "a explicit" and raise you an implicit frown.
    • "Mypy will support modular, efficient type checking, and this seems to rule out type checking some language features, such as arbitrary runtime addition of methods. However, it is likely that many of these features will be supported in a restricted form (for example, runtime modification is only supported for classes or methods registered as dynamic or ‘patchable’)."
    • For a full list of syntactic incompatibilities, see "Dealing with common issues". It's not pretty. You just wanted type checking and now you refactored your entire codebase and broke everyone's build two days from the candidate release and the comely HR midget in casual business attire slips a pink slip through the crack in your cubicle-cum-mancave. Thanks alot, mypy.
  • A performance penalty, despite interpreting statically typed code. Fourty years of hard-boiled computer science tells us that (...all else being equal) interpreting statically typed code should be faster, not slower, than interpreting dynamically typed code. In Python, up is the new down.
  • Additional non-trivial dependencies, increasing:
    • The bug-laden fragility of project deployment, especially cross-platform.
    • The maintenance burden of project development.
    • Possible attack surface.

I ask Guido: "Why? Why bother inventing an abstract API if you weren't willing to pony up a concrete API actually doing something with that abstraction?" Why leave the fate of a million Pythonistas to the arthritic hand of the free open-source marketplace? Why create yet another techno-problem that could have been trivially solved with a 275-line decorator in the official Python stdlib?

I have no Python and I must scream.

How to allow users to check for the latest app version from inside the app?

I did using in-app updates. This will only with devices running Android 5.0 (API level 21) or higher,

sed one-liner to convert all uppercase to lowercase?

I like some of the answers here, but there is a sed command that should do the trick on any platform:

sed 'y/ABCDEFGHIJKLMNOPQRSTUVWXYZ/abcdefghijklmnopqrstuvwxyz/'

Anyway, it's easy to understand. And knowing about the y command can come in handy sometimes.

Adding a newline character within a cell (CSV)

On Excel for Mac 2011, the newline had to be a \r instead of an \n

So

"\"first line\rsecond line\""

would show up as a cell with 2 lines

Can we add div inside table above every <tr>?

You could use display: table-row-group for your div.

<table>
  <div style="display: table-row-group">
    <tr><td></td></tr>
  </div>
  <div style="display: table-row-group">
    <tr><td></td></tr>
  </div>
</table>

Unable to locate an executable at "/usr/bin/java/bin/java" (-1)

Most certainly, export JAVA_HOME=/usr/bin/java is the culprit. This env var should point to the JDK or JRE installation directory. Googling shows that the best option for MacOS X seems to be export JAVA_HOME=/Library/Java/Home.

C# LINQ select from list

In likeness of how I found this question using Google, I wanted to take it one step further. Lets say I have a string[] states and a db Entity of StateCounties and I just want the states from the list returned and not all of the StateCounties.

I would write:

db.StateCounties.Where(x => states.Any(s => x.State.Equals(s))).ToList();

I found this within the sample of CheckBoxList for nu-get.

javascript scroll event for iPhone/iPad?

The iPhoneOS does capture onscroll events, except not the way you may expect.

One-finger panning doesn’t generate any events until the user stops panning—an onscroll event is generated when the page stops moving and redraws—as shown in Figure 6-1.

Similarly, scroll with 2 fingers fires onscroll only after you've stopped scrolling.

The usual way of installing the handler works e.g.

window.addEventListener('scroll', function() { alert("Scrolled"); });
// or
$(window).scroll(function() { alert("Scrolled"); });
// or
window.onscroll = function() { alert("Scrolled"); };
// etc 

(See also https://developer.apple.com/library/content/documentation/AppleApplications/Reference/SafariWebContent/HandlingEvents/HandlingEvents.html)

Convert string to int if string is a number

Use IsNumeric. It returns true if it's a number or false otherwise.

Public Sub NumTest()
    On Error GoTo MyErrorHandler

    Dim myVar As Variant
    myVar = 11.2 'Or whatever

    Dim finalNumber As Integer
    If IsNumeric(myVar) Then
        finalNumber = CInt(myVar)
    Else
        finalNumber = 0
    End If

    Exit Sub

MyErrorHandler:
    MsgBox "NumTest" & vbCrLf & vbCrLf & "Err = " & Err.Number & _
        vbCrLf & "Description: " & Err.Description
End Sub

Mod in Java produces negative numbers

The problem here is that in Python the % operator returns the modulus and in Java it returns the remainder. These functions give the same values for positive arguments, but the modulus always returns positive results for negative input, whereas the remainder may give negative results. There's some more information about it in this question.

You can find the positive value by doing this:

int i = (((-1 % 2) + 2) % 2)

or this:

int i = -1 % 2;
if (i<0) i += 2;

(obviously -1 or 2 can be whatever you want the numerator or denominator to be)

How do I catch an Ajax query post error?

A simple way is to implement ajaxError:

Whenever an Ajax request completes with an error, jQuery triggers the ajaxError event. Any and all handlers that have been registered with the .ajaxError() method are executed at this time.

For example:

$('.log').ajaxError(function() {
  $(this).text('Triggered ajaxError handler.');
});

I would suggest reading the ajaxError documentation. It does more than the simple use-case demonstrated above - mainly its callback accepts a number of parameters:

$('.log').ajaxError(function(e, xhr, settings, exception) {
  if (settings.url == 'ajax/missing.html') {
    $(this).text('Triggered ajaxError handler.');
  }
});

Create <div> and append <div> dynamically

Use the same process. You already have the variable iDiv which still refers to the original element <div id='block'> you've created. You just need to create another <div> and call appendChild().

// Your existing code unmodified...
var iDiv = document.createElement('div');
iDiv.id = 'block';
iDiv.className = 'block';
document.getElementsByTagName('body')[0].appendChild(iDiv);

// Now create and append to iDiv
var innerDiv = document.createElement('div');
innerDiv.className = 'block-2';

// The variable iDiv is still good... Just append to it.
iDiv.appendChild(innerDiv);

http://jsfiddle.net/W4Sup/1/

The order of event creation doesn't have to be as I have it above. You can alternately append the new innerDiv to the outer div before you add both to the <body>.

var iDiv = document.createElement('div');
iDiv.id = 'block';
iDiv.className = 'block';

// Create the inner div before appending to the body
var innerDiv = document.createElement('div');
innerDiv.className = 'block-2';

// The variable iDiv is still good... Just append to it.
iDiv.appendChild(innerDiv);

// Then append the whole thing onto the body
document.getElementsByTagName('body')[0].appendChild(iDiv);

How to get two or more commands together into a batch file

If you are creating other batch files from your outputs then put a line like this in your batch file

echo %pathname%\foo.exe >part2.txt

then you can have your defined part1.txt and part3.txt already done and have your batch

copy part1.txt + part2.txt +part3.txt thebatyouwanted.bat

What is the difference between ArrayList.clear() and ArrayList.removeAll()?

The clear() method removes all the elements of a single ArrayList. It's a fast operation, as it just sets the array elements to null.

The removeAll(Collection) method, which is inherited from AbstractCollection, removes all the elements that are in the argument collection from the collection you call the method on. It's a relatively slow operation, as it has to search through one of the collections involved.

Database design for a survey

Having a large Answer table, in and of itself, is not a problem. As long as the indexes and constraints are well defined you should be fine. Your second schema looks good to me.

How to replace NA values in a table for selected columns

This is now trivial in tidyr with replace_na(). The function appears to work for data.tables as well as data.frames:

tidyr::replace_na(x, list(a=0, b=0))

Changing datagridview cell color based on condition

I know this is an old post, but I found my way here in 2018, so maybe someone else will too. In my opinion, the OP had a better approach (using dgv_DataBindingComplete event) than any of the answers provided. At the time of writing, all of the answers are written using paint events or cellformatting events which seems inefficient.

The OP was 99% of the way there, all they had to do was loop through their rows, test the cell value of each row, and set the BackColor, ForeColor, or whatever other property you want to set.

Please excuse the vb.NET syntax, but I think its close enough to C# that it should be clear.

Private Sub dgvFinancialResults_DataBindingComplete Handles dgvFinancialResults.DataBindingComplete
            Try
                Logging.TraceIt()
                For Each row As DataGridViewRow in dgvFinancialResults.Rows
                    Dim invoicePricePercentChange = CSng(row.Cells("Invoice Price % Change").Value)
                    Dim netPricePercentChange = CSng(row.Cells("Net Price % Change").Value)
                    Dim tradespendPricePercentChange = CSng(row.Cells("Trade Spend % Change").Value)
                    Dim dnnsiPercentChange = CSng(row.Cells("DNNSI % Change").Value)
                    Dim cogsPercentChange = CSng(row.Cells("COGS % Change").Value)
                    Dim grossProfitPercentChange = CSng(row.Cells("Gross Profit % Change").Value)


                    If invoicePricePercentChange > Single.Epsilon Then
                        row.Cells("Invoice Price % Change").Style.ForeColor = Color.Green
                    Else
                        row.Cells("Invoice Price % Change").Style.ForeColor = Color.Red
                    End If

                    If netPricePercentChange > Single.Epsilon Then
                        row.Cells("Net Price % Change").Style.ForeColor = Color.Green
                    Else
                        row.Cells("Net Price % Change").Style.ForeColor = Color.Red
                    End If

                    If tradespendPricePercentChange > Single.Epsilon Then
                        row.Cells("Trade Spend % Change").Style.ForeColor = Color.Green
                    Else
                        row.Cells("Trade Spend % Change").Style.ForeColor = Color.Red
                    End If

                    If dnnsiPercentChange > Single.Epsilon Then
                        row.Cells("DNNSI % Change").Style.ForeColor = Color.Green
                    Else
                        row.Cells("DNNSI % Change").Style.ForeColor = Color.Red
                    End If

                    If cogsPercentChange > Single.Epsilon Then
                        row.Cells("COGS % Change").Style.ForeColor = Color.Green
                    Else
                        row.Cells("COGS % Change").Style.ForeColor = Color.Red
                    End If

                    If grossProfitPercentChange > Single.Epsilon Then
                        row.Cells("Gross Profit % Change").Style.ForeColor = Color.Green
                    Else
                        row.Cells("Gross Profit % Change").Style.ForeColor = Color.Red
                    End If
                Next
            Catch ex As Exception
                Logging.ErrorHandler(ex)
            End Try
        End Sub

Animate visibility modes, GONE and VISIBLE

This is a quite old question, still comments show, that still people have problems, so here is my solution with following additional features:

  • adjust the animation (speed, type, ...)
  • does not need to extend any class
  • in my case, animateLayoutChanges has problems in the new CoordinatorLayout

Function - Example (I have this function in an utility class)

public static void animateViewVisibility(final View view, final int visibility)
{
    // cancel runnning animations and remove and listeners
    view.animate().cancel();
    view.animate().setListener(null);

    // animate making view visible
    if (visibility == View.VISIBLE)
    {
        view.animate().alpha(1f).start();
        view.setVisibility(View.VISIBLE);
    }
    // animate making view hidden (HIDDEN or INVISIBLE)
    else
    {
        view.animate().setListener(new AnimatorListenerAdapter()
        {
            @Override
            public void onAnimationEnd(Animator animation)
            {
                view.setVisibility(visibility);
            }
        }).alpha(0f).start();
    }
}

Adjust animation

After calling view.animate() you can adjust the animation to whatever you want (set duration, set interpolator and more...). You may as well hide a view by scaling it instead of adjusting it's alpha value, just replace the alpha(...) with scaleX(...) or scaleY(...) in the utility method if you want that

Async always WaitingForActivation

this code seems to have address the issue for me. it comes for a streaming class, ergo some of the nomenclature.

''' <summary> Reference to the awaiting task. </summary>
''' <value> The awaiting task. </value>
Protected ReadOnly Property AwaitingTask As Threading.Tasks.Task

''' <summary> Reference to the Action task; this task status undergoes changes. </summary>
Protected ReadOnly Property ActionTask As Threading.Tasks.Task

''' <summary> Reference to the cancellation source. </summary>
Protected ReadOnly Property TaskCancellationSource As Threading.CancellationTokenSource

''' <summary> Starts the action task. </summary>
''' <param name="taskAction"> The action to stream the entities, which calls
'''                           <see cref="StreamEvents(Of T)(IEnumerable(Of T), IEnumerable(Of Date), Integer, String)"/>. </param>
''' <returns> The awaiting task. </returns>
Private Async Function AsyncAwaitTask(ByVal taskAction As Action) As Task
    Me._ActionTask = Task.Run(taskAction)
    Await Me.ActionTask '  Task.Run(streamEntitiesAction)
    Try
        Me.ActionTask?.Wait()
        Me.OnStreamTaskEnded(If(Me.ActionTask Is Nothing, TaskStatus.RanToCompletion, Me.ActionTask.Status))
    Catch ex As AggregateException
        Me.OnExceptionOccurred(ex)
    Finally
        Me.TaskCancellationSource.Dispose()
    End Try
End Function

''' <summary> Starts Streaming the events. </summary>
''' <exception cref="InvalidOperationException"> Thrown when the requested operation is invalid. </exception>
''' <param name="bucketKey">            The bucket key. </param>
''' <param name="timeout">              The timeout. </param>
''' <param name="streamEntitiesAction"> The action to stream the entities, which calls
'''                                     <see cref="StreamEvents(Of T)(IEnumerable(Of T), IEnumerable(Of Date), Integer, String)"/>. </param>
Public Overridable Sub StartStreamEvents(ByVal bucketKey As String, ByVal timeout As TimeSpan, ByVal streamEntitiesAction As Action)
    If Me.IsTaskActive Then
        Throw New InvalidOperationException($"Stream task is {Me.ActionTask.Status}")
    Else
        Me._TaskCancellationSource = New Threading.CancellationTokenSource
        Me.TaskCancellationSource.Token.Register(AddressOf Me.StreamTaskCanceled)
        Me.TaskCancellationSource.CancelAfter(timeout)
        ' the action class is created withing the Async/Await function
        Me._AwaitingTask = Me.AsyncAwaitTask(streamEntitiesAction)
    End If
End Sub

How to convert a list into data table

Just add this function and call it, it will convert List to DataTable.

public static DataTable ToDataTable<T>(List<T> items)
{
        DataTable dataTable = new DataTable(typeof(T).Name);

        //Get all the properties
        PropertyInfo[] Props = typeof(T).GetProperties(BindingFlags.Public | BindingFlags.Instance);
        foreach (PropertyInfo prop in Props)
        {
            //Defining type of data column gives proper data table 
            var type = (prop.PropertyType.IsGenericType && prop.PropertyType.GetGenericTypeDefinition() == typeof(Nullable<>) ? Nullable.GetUnderlyingType(prop.PropertyType) : prop.PropertyType);
            //Setting column names as Property names
            dataTable.Columns.Add(prop.Name, type);
        }
        foreach (T item in items)
        {
           var values = new object[Props.Length];
           for (int i = 0; i < Props.Length; i++)
           {
                //inserting property values to datatable rows
                values[i] = Props[i].GetValue(item, null);
           }
           dataTable.Rows.Add(values);
      }
      //put a breakpoint here and check datatable
      return dataTable;
}

S3 Static Website Hosting Route All Paths to Index.html

The way I was able to get this to work is as follows:

In the Edit Redirection Rules section of the S3 Console for your domain, add the following rules:

<RoutingRules>
  <RoutingRule>
    <Condition>
      <HttpErrorCodeReturnedEquals>404</HttpErrorCodeReturnedEquals>
    </Condition>
    <Redirect>
      <HostName>yourdomainname.com</HostName>
      <ReplaceKeyPrefixWith>#!/</ReplaceKeyPrefixWith>
    </Redirect>
  </RoutingRule>
</RoutingRules>

This will redirect all paths that result in a 404 not found to your root domain with a hash-bang version of the path. So http://yourdomainname.com/posts will redirect to http://yourdomainname.com/#!/posts provided there is no file at /posts.

To use HTML5 pushStates however, we need to take this request and manually establish the proper pushState based on the hash-bang path. So add this to the top of your index.html file:

<script>
  history.pushState({}, "entry page", location.hash.substring(1));
</script>

This grabs the hash and turns it into an HTML5 pushState. From this point on you can use pushStates to have non-hash-bang paths in your app.

Display fullscreen mode on Tkinter

This will create a completely fullscreen window on mac (with no visible menubar) without messing up keybindings

import tkinter as tk
root = tk.Tk()

root.overrideredirect(True)
root.overrideredirect(False)
root.attributes('-fullscreen',True)


root.mainloop()

Return string without trailing slash

Try this:

function someFunction(site)     
{     
    return site.replace(/\/$/, "");
} 

AutoComplete TextBox Control

Check out the AutoCompleteSource, AutoCompleteCustomSource and AutoCompleteMode properties.

textBox1.AutoCompleteMode = AutoCompleteMode.Suggest;
textBox1.AutoCompleteSource = AutoCompleteSource.CustomSource;
AutoCompleteStringCollection col = new AutoCompleteStringCollection();
col.Add("Foo");
col.Add("Bar");
textBox1.AutoCompleteCustomSource = col;

Note that the designer allows you to do that without writing any code...

How do you clear your Visual Studio cache on Windows Vista?

The accepted answer gave two locations:

here

C:\Documents and Settings\Administrator\Local Settings\Temp\VWDWebCache

and possibly here

C:\Documents and Settings\Administrator\Local Settings\Application Data\Microsoft\WebsiteCache

Did you try those?

Edited to add

On my Windows Vista machine, it's located in

%Temp%\VWDWebCache

and in

%LocalAppData%\Microsoft\WebsiteCache

From your additional information (regarding team edition) this comes from Clear Client TFS Cache:

Clear Client TFS Cache

Visual Studio and Team Explorer provide a caching mechanism which can get out of sync. If I have multiple instances of a single TFS which can be connected to from a single Visual Studio client, that client can become confused.

To solve it..

For Windows Vista delete contents of this folder

%LocalAppData%\Microsoft\Team Foundation\1.0\Cache

How to get the nth occurrence in a string?

function getStringReminder(str, substr, occ) {
   let index = str.indexOf(substr);
   let preindex = '';
   let i = 1;
   while (index !== -1) {
      preIndex = index;
      if (occ == i) {
        break;
      }
      index = str.indexOf(substr, index + 1)
      i++;
   }
   return preIndex;
}
console.log(getStringReminder('bcdefgbcdbcd', 'bcd', 3));

SQL command to display history of queries

For MySQL > 5.1.11 or MariaDB

  1. SET GLOBAL log_output = 'TABLE';
  2. SET GLOBAL general_log = 'ON';
  3. Take a look at the table mysql.general_log

If you want to output to a log file:

  1. SET GLOBAL log_output = "FILE";
  2. SET GLOBAL general_log_file = "/path/to/your/logfile.log"
  3. SET GLOBAL general_log = 'ON';

As mentioned by jeffmjack in comments, these settings will be forgetting before next session unless you edit the configuration files (e.g. edit /etc/mysql/my.cnf, then restart to apply changes).

Now, if you'd like you can tail -f /var/log/mysql/mysql.log

More info here: Server System Variables

Installing Numpy on 64bit Windows 7 with Python 2.7.3

You may also try this, anaconda http://continuum.io/downloads

But you need to modify your environment variable PATH, so that the anaconda folder is before the original Python folder.

Java URLConnection Timeout

You can manually force disconnection by a Thread sleep. This is an example:

URLConnection con = url.openConnection();
con.setConnectTimeout(5000);
con.setReadTimeout(5000);
new Thread(new InterruptThread(con)).start();

then

public class InterruptThread implements Runnable {

    HttpURLConnection con;
    public InterruptThread(HttpURLConnection con) {
        this.con = con;
    }

    public void run() {
        try {
            Thread.sleep(5000); // or Thread.sleep(con.getConnectTimeout())
        } catch (InterruptedException e) {

        }
        con.disconnect();
        System.out.println("Timer thread forcing to quit connection");
    }
}

Undefined symbols for architecture x86_64 on Xcode 6.1

I just had the exact same error, and solved it by restarting xcode.

For me the issue occurred after an svn update, the file in question was added to the projects folder, but it never appeared in xcode(9.3.1) – until I restarted it.

Creating a new empty branch for a new project

On base this answer from Hiery Nomus.

You can create a branch as an orphan:

git checkout --orphan <branchname>

This will create a new branch with no parents. Then, you can clear the working directory with:

git rm --cached -r .

And then you just commit branch with empty commit and then push

git commit -m <commit message> --allow-empty
git push origin <newbranch>

Change app language programmatically in Android

Just handle in method

@Override public void onConfigurationChanged(android.content.res.Configuration newConfig).

Follow the Link

I think it is useful

Android: Pass data(extras) to a fragment

I prefer Serializable = no boilerplate code. For passing data to other Fragments or Activities the speed difference to a Parcelable does not matter.

I would also always provide a helper method for a Fragment or Activity, this way you always know, what data has to be passed. Here an example for your ListMusicFragment:

private static final String EXTRA_MUSIC_LIST = "music_list";

public static ListMusicFragment createInstance(List<Music> music) {
    ListMusicFragment fragment = new ListMusicFragment();
    Bundle bundle = new Bundle();
    bundle.putSerializable(EXTRA_MUSIC_LIST, music);
    fragment.setArguments(bundle);
    return fragment;
}

@Override
public View onCreateView(...) { 
    ...
    Bundle bundle = intent.getArguments();
    List<Music> musicList = (List<Music>)bundle.getSerializable(EXTRA_MUSIC_LIST);
    ...
}

Kotlin unresolved reference in IntelliJ

Had the same with IDEA 14.1.5, Kotlin v.1.0.0-beta-1038-IJ141-17.
Kotlin gets its own list entry (like Java) when creating new project, but the only working config was:

New | Project | Java | "Kotlin (Java)" (make sure you have Project SDK configured, too)
use library: Create, "Copy to: lib".

CSS transition shorthand with multiple properties?

If you have several specific properties that you want to transition in the same way (because you also have some properties you specifically don't want to transition, say opacity), another option is to do something like this (prefixes omitted for brevity):

.myclass {
    transition: all 200ms ease;
    transition-property: box-shadow, height, width, background, font-size;
}

The second declaration overrides the all in the shorthand declaration above it and makes for (occasionally) more concise code.

_x000D_
_x000D_
/* prefixes omitted for brevity */_x000D_
.box {_x000D_
    height: 100px;_x000D_
    width: 100px;_x000D_
    background: red;_x000D_
    box-shadow: red 0 0 5px 1px;_x000D_
    transition: all 500ms ease;_x000D_
    /*note: not transitioning width */_x000D_
    transition-property: height, background, box-shadow;_x000D_
}_x000D_
_x000D_
.box:hover {_x000D_
  height: 50px;_x000D_
  width: 50px;_x000D_
  box-shadow: blue 0 0 10px 3px;_x000D_
  background: blue;_x000D_
}
_x000D_
<p>Hover box for demo</p>_x000D_
<div class="box"></div>
_x000D_
_x000D_
_x000D_

Demo

Unable to read repository at http://download.eclipse.org/releases/indigo

I had the same problem and resolved it by

  • Deleting the cache directory \eclipse\p2\org.eclipse.equinox.p2.repository\cache
  • Refreshing the repositories.
    • Preferences -> Install Update -> Available Software Sites => select the entry
    • Click the "Reload"

What does double question mark (??) operator mean in PHP

$x = $y ?? 'dev'

is short hand for x = y if y is set, otherwise x = 'dev'

There is also

$x = $y =="SOMETHING" ? 10 : 20

meaning if y equals 'SOMETHING' then x = 10, otherwise x = 20

Hamcrest compare collections

To compare two lists with the order preserved use,

assertThat(actualList, contains("item1","item2"));

What is the difference between pip and conda?

Not to confuse you further, but you can also use pip within your conda environment, which validates the general vs. python specific managers comments above.

conda install -n testenv pip
source activate testenv
pip <pip command>

you can also add pip to default packages of any environment so it is present each time so you don't have to follow the above snippet.

How to create Python egg file

You are reading the wrong documentation. You want this: https://setuptools.readthedocs.io/en/latest/setuptools.html#develop-deploy-the-project-source-in-development-mode

  1. Creating setup.py is covered in the distutils documentation in Python's standard library documentation here. The main difference (for python eggs) is you import setup from setuptools, not distutils.

  2. Yep. That should be right.

  3. I don't think so. pyc files can be version and platform dependent. You might be able to open the egg (they should just be zip files) and delete .py files leaving .pyc files, but it wouldn't be recommended.

  4. I'm not sure. That might be “Development Mode”. Or are you looking for some “py2exe” or “py2app” mode?

What is String pool in Java?

Let's start with a quote from the virtual machine spec:

Loading of a class or interface that contains a String literal may create a new String object (§2.4.8) to represent that literal. This may not occur if the a String object has already been created to represent a previous occurrence of that literal, or if the String.intern method has been invoked on a String object representing the same string as the literal.

This may not occur - This is a hint, that there's something special about String objects. Usually, invoking a constructor will always create a new instance of the class. This is not the case with Strings, especially when String objects are 'created' with literals. Those Strings are stored in a global store (pool) - or at least the references are kept in a pool, and whenever a new instance of an already known Strings is needed, the vm returns a reference to the object from the pool. In pseudo code, it may go like that:

1: a := "one" 
   --> if(pool[hash("one")] == null)  // true
           pool[hash("one") --> "one"]
       return pool[hash("one")]

2: b := "one" 
  --> if(pool[hash("one")] == null)   // false, "one" already in pool
        pool[hash("one") --> "one"]
      return pool[hash("one")] 

So in this case, variables a and b hold references to the same object. IN this case, we have (a == b) && (a.equals(b)) == true.

This is not the case if we use the constructor:

1: a := "one"
2: b := new String("one")

Again, "one" is created on the pool but then we create a new instance from the same literal, and in this case, it leads to (a == b) && (a.equals(b)) == false

So why do we have a String pool? Strings and especially String literals are widely used in typical Java code. And they are immutable. And being immutable allowed to cache String to save memory and increase performance (less effort for creation, less garbage to be collected).

As programmers we don't have to care much about the String pool, as long as we keep in mind:

  • (a == b) && (a.equals(b)) may be true or false (always use equals to compare Strings)
  • Don't use reflection to change the backing char[] of a String (as you don't know who is actualling using that String)

Remove style attribute from HTML tags

You could handle it client side, the easiest would be with jQuery. Something like:

$("#tinyMce p").removeAttr("style");

How to determine equality for two JavaScript objects?

This is my version. It is using new Object.keys feature that is introduced in ES5 and ideas/tests from +, + and +:

_x000D_
_x000D_
function objectEquals(x, y) {_x000D_
    'use strict';_x000D_
_x000D_
    if (x === null || x === undefined || y === null || y === undefined) { return x === y; }_x000D_
    // after this just checking type of one would be enough_x000D_
    if (x.constructor !== y.constructor) { return false; }_x000D_
    // if they are functions, they should exactly refer to same one (because of closures)_x000D_
    if (x instanceof Function) { return x === y; }_x000D_
    // if they are regexps, they should exactly refer to same one (it is hard to better equality check on current ES)_x000D_
    if (x instanceof RegExp) { return x === y; }_x000D_
    if (x === y || x.valueOf() === y.valueOf()) { return true; }_x000D_
    if (Array.isArray(x) && x.length !== y.length) { return false; }_x000D_
_x000D_
    // if they are dates, they must had equal valueOf_x000D_
    if (x instanceof Date) { return false; }_x000D_
_x000D_
    // if they are strictly equal, they both need to be object at least_x000D_
    if (!(x instanceof Object)) { return false; }_x000D_
    if (!(y instanceof Object)) { return false; }_x000D_
_x000D_
    // recursive object equality check_x000D_
    var p = Object.keys(x);_x000D_
    return Object.keys(y).every(function (i) { return p.indexOf(i) !== -1; }) &&_x000D_
        p.every(function (i) { return objectEquals(x[i], y[i]); });_x000D_
}_x000D_
_x000D_
_x000D_
///////////////////////////////////////////////////////////////_x000D_
/// The borrowed tests, run them by clicking "Run code snippet"_x000D_
///////////////////////////////////////////////////////////////_x000D_
var printResult = function (x) {_x000D_
    if (x) { document.write('<div style="color: green;">Passed</div>'); }_x000D_
    else { document.write('<div style="color: red;">Failed</div>'); }_x000D_
};_x000D_
var assert = { isTrue: function (x) { printResult(x); }, isFalse: function (x) { printResult(!x); } }_x000D_
assert.isTrue(objectEquals(null,null));_x000D_
assert.isFalse(objectEquals(null,undefined));_x000D_
assert.isFalse(objectEquals(/abc/, /abc/));_x000D_
assert.isFalse(objectEquals(/abc/, /123/));_x000D_
var r = /abc/;_x000D_
assert.isTrue(objectEquals(r, r));_x000D_
_x000D_
assert.isTrue(objectEquals("hi","hi"));_x000D_
assert.isTrue(objectEquals(5,5));_x000D_
assert.isFalse(objectEquals(5,10));_x000D_
_x000D_
assert.isTrue(objectEquals([],[]));_x000D_
assert.isTrue(objectEquals([1,2],[1,2]));_x000D_
assert.isFalse(objectEquals([1,2],[2,1]));_x000D_
assert.isFalse(objectEquals([1,2],[1,2,3]));_x000D_
_x000D_
assert.isTrue(objectEquals({},{}));_x000D_
assert.isTrue(objectEquals({a:1,b:2},{a:1,b:2}));_x000D_
assert.isTrue(objectEquals({a:1,b:2},{b:2,a:1}));_x000D_
assert.isFalse(objectEquals({a:1,b:2},{a:1,b:3}));_x000D_
_x000D_
assert.isTrue(objectEquals({1:{name:"mhc",age:28}, 2:{name:"arb",age:26}},{1:{name:"mhc",age:28}, 2:{name:"arb",age:26}}));_x000D_
assert.isFalse(objectEquals({1:{name:"mhc",age:28}, 2:{name:"arb",age:26}},{1:{name:"mhc",age:28}, 2:{name:"arb",age:27}}));_x000D_
_x000D_
Object.prototype.equals = function (obj) { return objectEquals(this, obj); };_x000D_
var assertFalse = assert.isFalse,_x000D_
    assertTrue = assert.isTrue;_x000D_
_x000D_
assertFalse({}.equals(null));_x000D_
assertFalse({}.equals(undefined));_x000D_
_x000D_
assertTrue("hi".equals("hi"));_x000D_
assertTrue(new Number(5).equals(5));_x000D_
assertFalse(new Number(5).equals(10));_x000D_
assertFalse(new Number(1).equals("1"));_x000D_
_x000D_
assertTrue([].equals([]));_x000D_
assertTrue([1,2].equals([1,2]));_x000D_
assertFalse([1,2].equals([2,1]));_x000D_
assertFalse([1,2].equals([1,2,3]));_x000D_
assertTrue(new Date("2011-03-31").equals(new Date("2011-03-31")));_x000D_
assertFalse(new Date("2011-03-31").equals(new Date("1970-01-01")));_x000D_
_x000D_
assertTrue({}.equals({}));_x000D_
assertTrue({a:1,b:2}.equals({a:1,b:2}));_x000D_
assertTrue({a:1,b:2}.equals({b:2,a:1}));_x000D_
assertFalse({a:1,b:2}.equals({a:1,b:3}));_x000D_
_x000D_
assertTrue({1:{name:"mhc",age:28}, 2:{name:"arb",age:26}}.equals({1:{name:"mhc",age:28}, 2:{name:"arb",age:26}}));_x000D_
assertFalse({1:{name:"mhc",age:28}, 2:{name:"arb",age:26}}.equals({1:{name:"mhc",age:28}, 2:{name:"arb",age:27}}));_x000D_
_x000D_
var a = {a: 'text', b:[0,1]};_x000D_
var b = {a: 'text', b:[0,1]};_x000D_
var c = {a: 'text', b: 0};_x000D_
var d = {a: 'text', b: false};_x000D_
var e = {a: 'text', b:[1,0]};_x000D_
var i = {_x000D_
    a: 'text',_x000D_
    c: {_x000D_
        b: [1, 0]_x000D_
    }_x000D_
};_x000D_
var j = {_x000D_
    a: 'text',_x000D_
    c: {_x000D_
        b: [1, 0]_x000D_
    }_x000D_
};_x000D_
var k = {a: 'text', b: null};_x000D_
var l = {a: 'text', b: undefined};_x000D_
_x000D_
assertTrue(a.equals(b));_x000D_
assertFalse(a.equals(c));_x000D_
assertFalse(c.equals(d));_x000D_
assertFalse(a.equals(e));_x000D_
assertTrue(i.equals(j));_x000D_
assertFalse(d.equals(k));_x000D_
assertFalse(k.equals(l));_x000D_
_x000D_
// from comments on stackoverflow post_x000D_
assert.isFalse(objectEquals([1, 2, undefined], [1, 2]));_x000D_
assert.isFalse(objectEquals([1, 2, 3], { 0: 1, 1: 2, 2: 3 }));_x000D_
assert.isFalse(objectEquals(new Date(1234), 1234));_x000D_
_x000D_
// no two different function is equal really, they capture their context variables_x000D_
// so even if they have same toString(), they won't have same functionality_x000D_
var func = function (x) { return true; };_x000D_
var func2 = function (x) { return true; };_x000D_
assert.isTrue(objectEquals(func, func));_x000D_
assert.isFalse(objectEquals(func, func2));_x000D_
assert.isTrue(objectEquals({ a: { b: func } }, { a: { b: func } }));_x000D_
assert.isFalse(objectEquals({ a: { b: func } }, { a: { b: func2 } }));
_x000D_
_x000D_
_x000D_

MySQLi count(*) always returns 1

Always try to do an associative fetch, that way you can easy get what you want in multiple case result

Here's an example

$result = $mysqli->query("SELECT COUNT(*) AS cityCount FROM myCity")
$row = $result->fetch_assoc();
echo $row['cityCount']." rows in table myCity.";

PHP CURL & HTTPS

One important note, the solution mentioned above will not work on local host, you have to upload your code to server and then it will work. I was getting no error, than bad request, the problem was I was using localhost (test.dev,myproject.git). Both solution above work, the solution that uses SSL cert is recommended.

  1. Go to https://curl.haxx.se/docs/caextract.html, download the latest cacert.pem. Store is somewhere (not in public folder - but will work regardless)

  2. Use this code

".$result; //echo "
Path:".$_SERVER['DOCUMENT_ROOT'] . "/ssl/cacert.pem"; // this is for troubleshooting only ?>
  1. Upload the code to live server and test.

Python - List of unique dictionaries

a = [
{'id':1,'name':'john', 'age':34},
{'id':1,'name':'john', 'age':34},
{'id':2,'name':'hanna', 'age':30},
]

b = {x['id']:x for x in a}.values()

print(b)

outputs:

[{'age': 34, 'id': 1, 'name': 'john'}, {'age': 30, 'id': 2, 'name': 'hanna'}]

How to make gradient background in android

Visual examples help with this kind of question.

Boilerplate

In order to create a gradient, you create an xml file in res/drawable. I am calling mine my_gradient_drawable.xml:

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <gradient
        android:type="linear"
        android:angle="0"
        android:startColor="#f6ee19"
        android:endColor="#115ede" />
</shape>

You set it to the background of some view. For example:

<View
    android:layout_width="200dp"
    android:layout_height="100dp"
    android:background="@drawable/my_gradient_drawable"/>

type="linear"

Set the angle for a linear type. It must be a multiple of 45 degrees.

<gradient
    android:type="linear"
    android:angle="0"
    android:startColor="#f6ee19"
    android:endColor="#115ede" />

enter image description here

type="radial"

Set the gradientRadius for a radial type. Using %p means it is a percentage of the smallest dimension of the parent.

<gradient
    android:type="radial"
    android:gradientRadius="10%p"
    android:startColor="#f6ee19"
    android:endColor="#115ede" />

enter image description here

type="sweep"

I don't know why anyone would use a sweep, but I am including it for completeness. I couldn't figure out how to change the angle, so I am only including one image.

<gradient
    android:type="sweep"
    android:startColor="#f6ee19"
    android:endColor="#115ede" />

enter image description here

center

You can also change the center of the sweep or radial types. The values are fractions of the width and height. You can also use %p notation.

android:centerX="0.2"
android:centerY="0.7"

enter image description here

JavaScript for...in vs for

There is an important difference between both. The for-in iterates over the properties of an object, so when the case is an array it will not only iterate over its elements but also over the "remove" function it has.

for (var i = 0; i < myArray.length; i++) { 
    console.log(i) 
}

//Output
0
1

for (var i in myArray) { 
    console.log(i) 
} 

// Output
0 
1 
remove

You could use the for-in with an if(myArray.hasOwnProperty(i)). Still, when iterating over arrays I always prefer to avoid this and just use the for(;;) statement.

Why can't I display a pound (£) symbol in HTML?

This works in all chrome, IE, Firefox.

In Database > table > field type .for example set the symbol column TO varchar(2) utf8_bin php code:

$symbol = '£';
echo mb_convert_encoding($symbol, 'UTF-8', 'HTML-ENTITIES');
or 
html_entity_decode($symbol, ENT_NOQUOTES, 'UTF-8');

And also make sure set the HTML OR XML encoding to encoding="UTF-8"

Note: You should make sure that database, document type and php code all have a same encoding

How ever the better solution would be using &pound;

How to close jQuery Dialog within the dialog?

After checking all of these answers above without luck, the folling code worked for me to solve the problem:

$(".ui-dialog").dialog("close");

Maybe this will be also a good try if you seek for alternatives.

mysqldump data only

This should work:

# To export to file (data only)
mysqldump -u [user] -p[pass] --no-create-info mydb > mydb.sql

# To export to file (structure only)
mysqldump -u [user] -p[pass] --no-data mydb > mydb.sql

# To import to database
mysql -u [user] -p[pass] mydb < mydb.sql

NOTE: there's no space between -p & [pass]

When do I have to use interfaces instead of abstract classes?

Actually Interface and abstract class are used to just specify some contract/rules which will just show, how their sub classes will be.

Mostly we know that interface is a pure abstract.Means there you cant specify a single method with body.This particular point is the advantages of abstract class.Means in abstract class u have right to specify method with body and without body as-well.

So if u want to specify something about ur subclass, then u may go for interface. But if u also want to specify something for ur sub classes and u want also ur class should also have some own method.Then in that case u may go for abstract class

Jenkins restrict view of jobs per user

Try going to "Manage Jenkins"->"Manage Users" go to the specific user, edit his/her configuration "My Views section" default view.

AngularJS view not updating on model change

setTimout executes outside of angular. You need to use $timeout service for this to work:

var app = angular.module('test', []);

    app.controller('TestCtrl', function ($scope, $timeout) {
       $scope.testValue = 0;

        $timeout(function() {
            console.log($scope.testValue++);
        }, 500);
    });

The reason is that two-way binding in angular uses dirty checking. This is a good article to read about angular's dirty checking. $scope.$apply() kicks off a $digest cycle. This will apply the binding. $timeout handles the $apply for you so it is the recommended service to use when using timeouts.

Essentially, binding happens during the $digest cycle (if the value is seen to be different).

How to convert ASCII code (0-255) to its corresponding character?

upper answer only near solving the Problem. heres your answer:

Integer.decode(Character.toString(char c));

Kubernetes Pod fails with CrashLoopBackOff

I faced similar issue "CrashLoopBackOff" when I debugged getting pods and logs of pod. Found out that my command arguments are wrong

What does "where T : class, new()" mean?

new(): Specifying the new() constraint means type T must use a parameterless constructor, so an object can be instantiated from it - see Default constructors.

class: Means T must be a reference type so it can't be an int, float, double, DateTime or other struct (value type).

public void MakeCars()
{
    //This won't compile as researchEngine doesn't have a public constructor and so can't be instantiated.
    CarFactory<ResearchEngine> researchLine = new CarFactory<ResearchEngine>();
    var researchEngine = researchLine.MakeEngine();

    //Can instantiate new object of class with default public constructor
    CarFactory<ProductionEngine> productionLine = new CarFactory<ProductionEngine>();
    var productionEngine = productionLine.MakeEngine();
}

public class ProductionEngine { }
public class ResearchEngine
{
    private ResearchEngine() { }
}

public class CarFactory<TEngine> where TEngine : class, new()
{
    public TEngine MakeEngine()
    {
        return new TEngine();
    }
}

Replace non-numeric with empty string

You don't need to use Regex.

phone = new String(phone.Where(c => char.IsDigit(c)).ToArray())

How do I add space between two variables after a print in Python

This is a stupid/hacky way

print count,    
print conv

Unable to compile simple Java 10 / Java 11 project with Maven

Specify maven.compiler.source and target versions.

1) Maven version which supports jdk you use. In my case JDK 11 and maven 3.6.0.

2) pom.xml

<properties>
    <maven.compiler.source>11</maven.compiler.source>
    <maven.compiler.target>11</maven.compiler.target>
</properties>

As an alternative, you can fully specify maven compiler plugin. See previous answers. It is shorter in my example :)

<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>3.8.0</version>
            <configuration>
                <release>11</release>
            </configuration>
        </plugin>
    </plugins>
</build>

3) rebuild the project to avoid compile errors in your IDE.

4) If it still does not work. In Intellij Idea I prefer using terminal instead of using terminal from OS. Then in Idea go to file -> settings -> build tools -> maven. I work with maven I downloaded from apache (by default Idea uses bundled maven). Restart Idea then and run mvn clean install again. Also make sure you have correct Path, MAVEN_HOME, JAVA_HOME environment variables.

I also saw this one-liner, but it does not work.

<maven.compiler.release>11</maven.compiler.release>

I made some quick starter projects, which I re-use in other my projects, feel free to check:

Using Caps Lock as Esc in Mac OS X

In order to actually swap the escape key with the caps lock key (not just map one to the other) using both PCKeyboardHack and KeyRemap4MacBook, you have to follow the instructions in this thread, mapping the caps lock key to a keycode not used by the keyboard but accounted for by KeyRemap4MacBook (eg. 110). Then, in PCKeyboardHack, select the appropriate option that maps that keycode to escape (in the case of 110, it's "Application Key to Escape"). Here's what your KeyRemap4MacBook preferences should look like (provided you've selected the "show enabled only" checkbox).

enter image description here

I originally attempted to post this information as an edit to cwd's excellent answer, but it was rejected. I encourage anyone who wants to go the route that I describe to first read his/her response.

Cleanest way to build an SQL string in Java

I am wondering if you are after something like Squiggle. Also something very useful is jDBI. It won't help you with the queries though.

What is the equivalent of the C++ Pair<L,R> in Java?

android provides Pairclass (http://developer.android.com/reference/android/util/Pair.html) , here the implementation:

public class Pair<F, S> {
    public final F first;
    public final S second;

    public Pair(F first, S second) {
        this.first = first;
        this.second = second;
    }

    @Override
    public boolean equals(Object o) {
        if (!(o instanceof Pair)) {
            return false;
        }
        Pair<?, ?> p = (Pair<?, ?>) o;
        return Objects.equal(p.first, first) && Objects.equal(p.second, second);
    }

    @Override
    public int hashCode() {
        return (first == null ? 0 : first.hashCode()) ^ (second == null ? 0 : second.hashCode());
    }

    public static <A, B> Pair <A, B> create(A a, B b) {
        return new Pair<A, B>(a, b);
    }
}

What does Maven do, in theory and in practice? When is it worth to use it?

What it does

Maven is a "build management tool", it is for defining how your .java files get compiled to .class, packaged into .jar (or .war or .ear) files, (pre/post)processed with tools, managing your CLASSPATH, and all others sorts of tasks that are required to build your project. It is similar to Apache Ant or Gradle or Makefiles in C/C++, but it attempts to be completely self-contained in it that you shouldn't need any additional tools or scripts by incorporating other common tasks like downloading & installing necessary libraries etc.

It is also designed around the "build portability" theme, so that you don't get issues as having the same code with the same buildscript working on one computer but not on another one (this is a known issue, we have VMs of Windows 98 machines since we couldn't get some of our Delphi applications compiling anywhere else). Because of this, it is also the best way to work on a project between people who use different IDEs since IDE-generated Ant scripts are hard to import into other IDEs, but all IDEs nowadays understand and support Maven (IntelliJ, Eclipse, and NetBeans). Even if you don't end up liking Maven, it ends up being the point of reference for all other modern builds tools.

Why you should use it

There are three things about Maven that are very nice.

  1. Maven will (after you declare which ones you are using) download all the libraries that you use and the libraries that they use for you automatically. This is very nice, and makes dealing with lots of libraries ridiculously easy. This lets you avoid "dependency hell". It is similar to Apache Ant's Ivy.

  2. It uses "Convention over Configuration" so that by default you don't need to define the tasks you want to do. You don't need to write a "compile", "test", "package", or "clean" step like you would have to do in Ant or a Makefile. Just put the files in the places in which Maven expects them and it should work off of the bat.

  3. Maven also has lots of nice plug-ins that you can install that will handle many routine tasks from generating Java classes from an XSD schema using JAXB to measuring test coverage with Cobertura. Just add them to your pom.xml and they will integrate with everything else you want to do.

The initial learning curve is steep, but (nearly) every professional Java developer uses Maven or wishes they did. You should use Maven on every project although don't be surprised if it takes you a while to get used to it and that sometimes you wish you could just do things manually, since learning something new sometimes hurts. However, once you truly get used to Maven you will find that build management takes almost no time at all.

How to Start

The best place to start is "Maven in 5 Minutes". It will get you start with a project ready for you to code in with all the necessary files and folders set-up (yes, I recommend using the quickstart archetype, at least at first).

After you get started you'll want a better understanding over how the tool is intended to be used. For that "Better Builds with Maven" is the most thorough place to understand the guts of how it works, however, "Maven: The Complete Reference" is more up-to-date. Read the first one for understanding, but then use the second one for reference.

How do you configure an OpenFileDialog to select folders?

You can subclass the file dialog and gain access to all its controls. Each has an identifier that can be used to obtain its window handle. You can then show and hide them, get messages from them about selection changes etc. etc. It all depends how much effort you want to take.

We did ours using WTL class support and customized the file dialog to include a custom places bar and plug-in COM views.

MSDN provides information on how to do this using Win32, this CodeProject article includes an example, and this CodeProject article provides a .NET example.

Soft keyboard open and close listener in an activity in Android

Found an accurate way of telling whether or not a keyboard when using the 'adjustResize' Soft input mode (Kotlin code)

Define a couple of activity scope variables

private var activityHeight = 0
private var keyboardOpen = false

Write the following code in onCreate

override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        
        ...

        /* Grab initial screen value */
        [email protected] {
            val displayFrame : Rect = Rect()
            [email protected](displayFrame)
            activityHeight = displayFrame.height()
        }

        /* Check for keyboard open/close */
        [email protected] { v, left, top, right, bottom, oldLeft, oldTop, oldRight, oldBottom ->
            val drawFrame : Rect = Rect()
            [email protected](drawFrame)
            val currentSize = drawFrame.height()

            keyboardOpen = currentSize < activityHeight
            Log.v("keyboard1","$keyboardOpen $currentSize - $activityHeight")
        }
}

You now have a boolean which accurately tracks whether or not the keyboard is open, do what you will

SELECT FOR UPDATE with SQL Server

Try (updlock, rowlock)

How to verify that a specific method was not called using Mockito?

Use the second argument on the Mockito.verify method, as in:

Mockito.verify(dependency, Mockito.times(0)).someMethod()

Change directory in PowerShell

Unlike the CMD.EXE CHDIR or CD command, the PowerShell Set-Location cmdlet will change drive and directory, both. Get-Help Set-Location -Full will get you more detailed information on Set-Location, but the basic usage would be

PS C:\> Set-Location -Path Q:\MyDir

PS Q:\MyDir> 

By default in PowerShell, CD and CHDIR are alias for Set-Location.

(Asad reminded me in the comments that if the path contains spaces, it must be enclosed in quotes.)

Python object.__repr__(self) should be an expression?

Guideline: If you can succinctly provide an exact representation, format it as a Python expression (which implies that it can be both eval'd and copied directly into source code, in the right context). If providing an inexact representation, use <...> format.

There are many possible representations for any value, but the one that's most interesting for Python programmers is an expression that recreates the value. Remember that those who understand Python are the target audience—and that's also why inexact representations should include relevant context. Even the default <XXX object at 0xNNN>, while almost entirely useless, still provides type, id() (to distinguish different objects), and indication that no better representation is available.

Show Youtube video source into HTML5 video tag?

The <video> tag is meant to load in a video of a supported format (which may differ by browser).

YouTube embed links are not just videos, they are typically webpages that contain logic to detect what your user supports and how they can play the youtube video, using HTML5, or flash, or some other plugin based on what is available on the users PC. This is why you are having a difficult time using the video tag with youtube videos.

YouTube does offer a developer API to embed a youtube video into your page.

I made a JSFiddle as a live example: http://jsfiddle.net/zub16fgt/

And you can read more about the YouTube API here: https://developers.google.com/youtube/iframe_api_reference#Getting_Started

The Code can also be found below

In your HTML:

<div id="player"></div>

In your Javascript:

var onPlayerReady = function(event) {
    event.target.playVideo();  
};

// The first argument of YT.Player is an HTML element ID. 
// YouTube API will replace my <div id="player"> tag 
// with an iframe containing the youtube video.

var player = new YT.Player('player', {
    height: 320,
    width: 400,
    videoId : '6Dc1C77nra4',
    events : {
        'onReady' : onPlayerReady
    }
});

what is the difference between json and xml

XML uses a tag structures for presenting items, like <tag>item</tag>, so an XML document is a set of tags nested into each other. And JSON syntax looks like a construction from Javascript language, with all stuff like lists and dictionaries:

{
 'attrib' : 'value',
 'array' : [1, 2, 3]
}

So if you use JSON it's really simple to use a JSON strings in many script languages, especially Javascript and Python.

Foreach in a Foreach in MVC View

You have:

foreach (var category in Model.Categories)

and then

@foreach (var product in Model)

Based on that view and model it seems that Model is of type Product if yes then the second foreach is not valid. Actually the first one could be the one that is invalid if you return a collection of Product.

UPDATE:

You are right, I am returning the model of type Product. Also, I do understand what is wrong now that you've pointed it out. How am I supposed to do what I'm trying to do then if I can't do it this way?

I'm surprised your code compiles when you said you are returning a model of Product type. Here's how you can do it:

@foreach (var category in Model)
{
    <h3><u>@category.Name</u></h3>

    <div>
        <ul>    
            @foreach (var product in category.Products)
            {
                <li>
                    put the rest of your code
                </li>
            }
        </ul>
    </div>
}

That suggest that instead of returning a Product, you return a collection of Category with Products. Something like this in EF:

// I am typing it here directly 
// so I'm not sure if this is the correct syntax.
// I assume you know how to do this,
// anyway this should give you an idea.
context.Categories.Include(o=>o.Product)

Key hash for Android-Facebook app

keytool -exportcert -alias androiddebugkey -keystore       C:\Users\pravin\.android\debug.keystore | "H:\OpenSSL\bin\openssl" sha1 -binary | "H:\OpenSSL\bin\openssl" base64

This worked for me ...

Steps:

1) Open command line go to - > java Keytool..... for me C:\Program Files\Java\JDK1.7\bin
2) Download OpenSSL from google
3) paste this with changing your paths -
   keytool -exportcert -alias androiddebugkey -keystore C:\Users\pravin\.android\debug.keystore | "H:\OpenSSL\bin\openssl" sha1 -binary | "H:\OpenSSL\bin\openssl" base64 

    ....................   give proper debug.keystore path and openSSL path .. 

4) Finley it may be ask u password .. so give password -> android   ...
5) you will get 28 characters that will be your has key

Convert seconds into days, hours, minutes and seconds

A variation on @Glavic's answer - this one hides leading zeros for shorter results and uses plurals in correct places. It also removes unnecessary precision (e.g. if the time difference is over 2 hours, you probably don't care how many minutes or seconds).

function secondsToTime($seconds)
{
    $dtF = new \DateTime('@0');
    $dtT = new \DateTime("@$seconds");
    $dateInterval = $dtF->diff($dtT);
    $days_t = 'day';
    $hours_t = 'hour';
    $minutes_t = 'minute';
    $seconds_t = 'second';
    if ((int)$dateInterval->d > 1) {
        $days_t = 'days';
    }
    if ((int)$dateInterval->h > 1) {
        $hours_t = 'hours';
    }
    if ((int)$dateInterval->i > 1) {
        $minutes_t = 'minutes';
    }
    if ((int)$dateInterval->s > 1) {
        $seconds_t = 'seconds';
    }


    if ((int)$dateInterval->d > 0) {
        if ((int)$dateInterval->d > 1 || (int)$dateInterval->h === 0) {
            return $dateInterval->format("%a $days_t");
        } else {
            return $dateInterval->format("%a $days_t, %h $hours_t");
        }
    } else if ((int)$dateInterval->h > 0) {
        if ((int)$dateInterval->h > 1 || (int)$dateInterval->i === 0) {
            return $dateInterval->format("%h $hours_t");
        } else {
            return $dateInterval->format("%h $hours_t, %i $minutes_t");
        }
    } else if ((int)$dateInterval->i > 0) {
        if ((int)$dateInterval->i > 1 || (int)$dateInterval->s === 0) {
            return $dateInterval->format("%i $minutes_t");
        } else {
            return $dateInterval->format("%i $minutes_t, %s $seconds_t");
        }
    } else {
        return $dateInterval->format("%s $seconds_t");
    }

}
php > echo secondsToTime(60);
1 minute
php > echo secondsToTime(61);
1 minute, 1 second
php > echo secondsToTime(120);
2 minutes
php > echo secondsToTime(121);
2 minutes
php > echo secondsToTime(2000);
33 minutes
php > echo secondsToTime(4000);
1 hour, 6 minutes
php > echo secondsToTime(4001);
1 hour, 6 minutes
php > echo secondsToTime(40001);
11 hours
php > echo secondsToTime(400000);
4 days

Changing nav-bar color after scrolling?

How about the Intersection Observer API? This avoids the potential sluggishness from using the scroll event.

HTML

<nav class="navbar-fixed-top">Navbar</nav>
<main>
  <div class="content">Some content</div>
</main>

CSS

.navbar-fixed-top--scrolled changes the nav bar background color. It's added to the nav bar when the content div is no longer 100% visible as we scroll down.

.navbar-fixed-top {
  position: sticky;
  top: 0;
  height: 60px;
}

.navbar-fixed-top--scrolled {
  /* change background-color to whatever you want */
  background-color: grey;
}

JS

Create the observer to determine when the content div fully intersects with the browser viewport.

The callback function is called:

  • the first time the observer is initially asked to watch the target element
  • when content div is no longer fully visible (due to threshold: 1)
  • when content div becomes fully visible (due to threshold: 1)

isIntersecting indicates whether the content div (the target element) is fully intersecting with the observer's root (the browser viewport by default).

// callback function to be run whenever threshold is crossed in one direction or the other
const callback = (entries, observer) => {
  const entry = entries[0];
  
  // toggle class depending on if content div intersects with viewport
  const navBar = document.querySelector('.navbar-fixed-top');
  navBar.classList.toggle('navbar-fixed-top--scrolled', !entry.isIntersecting);
}

// options controls circumstances under which the observer's callback is invoked
const options = {
  // no root provided - by default browser viewport used to check target visibility
  // only detect if target element is fully visible or not
  threshold: [1]
};

const io = new IntersectionObserver(callback, options);

// observe content div 
const target = document.querySelector('.content');
io.observe(target);

IntersectionObserver options

The nav bar currently changes background color when the content div starts moving off the screen.

If we want the background to change as soon as the user scrolls, we can use the rootMargin property (top, right, bottom, left) and set the top margin to negative the height of the nav bar (60px in our case).

const options = {
  rootMargin: "-60px 0px 0px 0px",
  threshold: [1]
};

You can see all the above in action on CodePen. Kevin Powell also has a good explanation on this (Github & YouTube).

How to count frequency of characters in a string?

There is one more option and it looks quite nice. Since java 8 there is new method merge java doc

  public static void main(String[] args) {
    String s = "aaabbbcca";

    Map<Character, Integer> freqMap = new HashMap<>();
    for (int i = 0; i < s.length(); i++) {
        Character c = s.charAt(i);
        freqMap.merge(c, 1, (a, b) -> a + b);
    }
    freqMap.forEach((k, v) -> System.out.println(k + " and " + v));
}

Or even cleaner with ForEach

       for (Character c : s.toCharArray()) {
            freqMapSecond.merge(c, 1, Integer::sum);
           }

How to replace a character by a newline in Vim

With Vim on Windows, use Ctrl + Q in place of Ctrl + V.

In Python, how do you convert a `datetime` object to seconds?

Maybe off-the-topic: to get UNIX/POSIX time from datetime and convert it back:

>>> import datetime, time
>>> dt = datetime.datetime(2011, 10, 21, 0, 0)
>>> s = time.mktime(dt.timetuple())
>>> s
1319148000.0

# and back
>>> datetime.datetime.fromtimestamp(s)
datetime.datetime(2011, 10, 21, 0, 0)

Note that different timezones have impact on results, e.g. my current TZ/DST returns:

>>>  time.mktime(datetime.datetime(1970, 1, 1, 0, 0).timetuple())
-3600 # -1h

therefore one should consider normalizing to UTC by using UTC versions of the functions.

Note that previous result can be used to calculate UTC offset of your current timezone. In this example this is +1h, i.e. UTC+0100.

References: