Python virtualenv questions

Question

I m using VirtualEnv on Windows XP  I m wondering if I have my brain wrapped around it correctly   I ran virtualenv ENV and it created C  WINDOWS system32 ENV  I then changed my PATH variable to include C  WINDOWS system32 ENV Scripts instead of C  Python27 Scripts  Then  I checked out Django into C  WINDOWS system32 ENV Lib site-packages django-trunk  updated my PYTHON PATH variable to point the new Django directory  and continued to easy install other things  which of course go into my new C  WINDOWS system32 ENV Lib site-packages directory     I understand why I should use VirtualEnv so I can run multiple versions of Django  and other libraries on the same machine  but does this mean that to switch between environments I have to basically change my PATH and PYTHON PATH variable  So  I go from developing one Django project which uses Django 1 2 in an environment called ENV and then change my PATH and such so that I can use an environment called ENV2 which has the dev version of Django   Is that basically it  or is there some better way to automatically do all this  I could update my path in Python code  but that would require me to write machine-specific code in my application    Also  how does this process compare to using VirtualEnv on Linux  I m quite the beginner at Linux

User · Answer

in my project wsgi py file i have this code  it works with virtualenv django apache2 in windows and python 3 4   import os import sys DJANGO PATH   os path join os path abspath os path dirname   file           sys path append DJANGO PATH  sys path append  c  myproject env Scripts   sys path append  c  myproject env Lib site-packages   activate this    c  myproject env scripts activate this py  exec open activate this  read    from django core wsgi import get wsgi application os environ setdefault  DJANGO SETTINGS MODULE    myproject settings   application   get wsgi application     in virtualhost file conf i have   lt VirtualHost   80 gt      ServerName mysite     WSGIScriptAlias   c  myproject myproject myproject wsgi py     DocumentRoot c  myproject myproject       lt Directory   c  myproject myproject myproject   gt         Options  Indexes  FollowSymLinks  MultiViews        AllowOverride All       Require local     lt  Directory gt   lt  VirtualHost gt

User · Answer

on Windows I have python 3 7 installed and I still couldn t activate virtualenv from Gitbash with   Scripts activate although it worked from Powershell after running Set-ExecutionPolicy Unrestricted in Powershell and changing the setting to  Yes To All    I don t like Powershell and I like to use Gitbash  so to activate virtualenv in Gitbash first navigate to your project folder  use ls to list the contents of the folder and be sure you see  Scripts   Change directory to  Scripts  using cd Scripts  once you re in the  Scripts  path use   activate to activate virtualenv  Don t forget the space after the dot

User · Answer

Normally virtualenv creates environments in the current directory  Unless you re intending to create virtual environments in C  Windows system32 for some reason  I would use a different directory for environments   You shouldn t need to mess with paths  use the activate script  in  lt env gt  Scripts  to ensure that the Python executable and path are environment-specific  Once you ve done this  the command prompt changes to indicate the environment  You can then just invoke easy install and whatever you install this way will be installed into this environment  Use deactivate to set everything back to how it was before activation   Example   c  Temp gt virtualenv myenv New python executable in myenv Scripts python exe Installing setuptools                  done  c  Temp gt myenv Scripts activate  myenv  C  Temp gt deactivate C  Temp gt    Notice how I didn t need to specify a path for deactivate - activate does that for you  so that when activated  Python  will run the Python in the virtualenv  not your system Python   Try it - do an import sys  sys prefix and it should print the root of your environment    You can just activate a new environment to switch between environments projects  but you ll need to specify the whole path for activate so it knows which environment to activate  You shouldn t ever need to mess with PATH or PYTHONPATH explicitly   If you use Windows Powershell then you can take advantage of a wrapper  On Linux  the virtualenvwrapper  the link points to a port of this to Powershell  makes life with virtualenv even easier   Update  Not incorrect  exactly  but perhaps not quite in the spirit of virtualenv  You could take a different tack  for example  if you install Django and anything else you need for your site in your virtualenv  then you could work in your project directory  where you re developing your site  with the virtualenv activated  Because it was activated  your Python would find Django and anything else you d easy installed into the virtual environment  and because you re working in your project directory  your project files would be visible to Python  too   Further update  You should be able to use pip  distribute instead of setuptools  and just plain python setup py install with virtualenv  Just ensure you ve activated an environment before installing something into it

User · Answer

After creating virtual environment copy the activate bat file from Script folder of python and paste to it your environment and open cmd from your virtual environment and run activate bat file enter image description here

User · Answer

Yes basically this is what virtualenv do   and this is what the activate command is for  from the doc here       activate script      In a newly created virtualenv there   will be a bin activate shell script    or a Scripts activate bat batch file   on Windows       This will change your  PATH to   point to the virtualenv bin    directory  Unlike workingenv  this is   all it does  it s a convenience  But   if you use the complete path like    path to env bin python script py you   do not need to activate the   environment first  You have to use   source because it changes the   environment in-place  After activating   an environment you can use the   function deactivate to undo the   changes       The activate script will also modify   your shell prompt to indicate which   environment is currently active    so you should just use activate command which will do all that for you    gt   path to env bin activate bat

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