Is it possible to overwrite a function in PHP

Question

Can you declare a function like this     function ihatefooexamples      return  boo-foo         And then redeclare it somewhat like this     if    GET  foolevel      10     function ihatefooexamples        return  really boo-foo             Is it possible to overwrite a function that way   Any way

User · Answer

Depending on situation where you need this, maybe you can use anonymous functions like this:

$greet = function($name)
{
    echo('Hello ' . $name);
};

$greet('World');

...then you can set new function to the given variable any time

User · Answer

You cannot redeclare any functions in PHP  You can  however  override them  Check out overriding functions as well as renaming functions in order to save the function you re overriding if you want   So  keep in mind that when you override a function  you lose it  You may want to consider keeping it  but in a different name  Just saying   Also  if these are functions in classes that you re wanting to override  you would just need to create a subclass and redeclare the function in your class without having to do rename function and override function   Example   rename function  mysql connect    original mysql connect     override function  mysql connect     a  b    echo  DOING MY FUNCTION INSTEAD   return  a    b

User · Answer

I would include all functions of one case in an include file  and the others in another include   For instance simple inc would contain function boofoo     simple   and really inc would contain function boofoo     really    It helps the readability   maintenance of your program  having all functions of the same kind in the same inc   Then at the top of your main module    if    GET  foolevel      10        include  really inc         else       include  simple inc

User · Answer

You could use the PECL extension   runkit function redefine      Replace a function definition with a new implementation    but that is bad practise in my opinion  You are using functions  but check out the Decorator design pattern  Can borrow the basic idea from it

User · Answer

Monkey patch in namespace php    5 3  A less evasive method than modifying the interpreter is the monkey patch   Monkey patching is the art of replacing the actual implementation with a similar  patch  of your own    Ninja skills  Before you can monkey patch like a PHP Ninja we first have to understand PHPs namespaces   Since PHP 5 3 we got introduced to namespaces which you might at first glance denote to be equivalent to something like java packages perhaps  but it s not quite the same  Namespaces  in PHP  is a way to encapsulate scope by creating a hierarchy of focus  especially for functions and constants  As this topic  fallback to global functions  aims to explain   If you don t provide a namespace when calling a function  PHP first looks in the current namespace then moves down the hierarchy until it finds the first function declared within that  prefixed namespace and executes that  For our example if you are calling print r    from namespace My Awesome Namespace  What PHP does is to first look for a function called My Awesome Namespace print r    then My Awesome print r    then My print r    until it finds the PHP built in function in the global namespace  print r      You will not be able to define a function print r  object     in the global namespace because this will cause a name collision since a function with that name already exists   Expect a fatal error to the likes of   Fatal error  Cannot redeclare print r     But nothing stops you  however  from doing just that within the scope of a namespace   Patching the monkey  Say you have a script using several print r    calls   Example    lt  php      print r  some object           do some stuff      print r  another object           do some other stuff      print r  data object           do more stuff      print r  debug object     But you later change your mind and you want the output wrapped in  lt pre gt  lt  pre gt  tags instead  Ever happened to you    Before you go and change every call to print r    consider monkey patching instead   Example    lt  php     namespace MyNamespace           function print r  object                         echo   lt pre gt     print r  object  true     lt  pre gt                        print r  some object              do some stuff         print r  another object              do some other stuff         print r  data object              do more stuff         print r  debug object           Your script will now be using MyNamespace print r    instead of the global  print r     Works great for mocking unit tests   nJoy

User · Answer

No this will be a problem   PHP Variable Functions

User · Answer

A solution for the related case where you have an include file A that you can edit and want to override some of its functions in an include file B  or the main file    Main File    lt  php  Override true     An argument used in A php include   A php    include   B php    F1      gt    Include File A    lt  php if     Override       function F1     echo  This is F1   in A        gt    Include File B    lt  php    function F1     echo  This is F1   in B      gt    Browsing to the main file displays  This is F1   in B

User · Answer

Edit     To address comments that this answer doesn t directly address the   original question  If you got here from a Google Search  start here   There is a function available called override function that actually fits the bill  However  given that this function is part of The Advanced PHP Debugger extension  it s hard to make an argument that override function   is intended for production use  Therefore  I would say  No   it is not possible to overwrite a function with the intent that the original questioner had in mind   Original Answer  This is where you should take advantage of OOP  specifically polymorphism   interface Fooable       public function ihatefooexamples       class Foo implements Fooable       public function ihatefooexamples                 return  boo-foo             class FooBar implements Fooable       public function ihatefooexamples                 return  really boo-foo             foo   new Foo     if  10      GET  foolevel           foo   new FooBar       echo  foo- gt ihatefooexamples

User · Answer

Have a look at override function to override the functions      override function     Overrides built-in   functions   Example   override function  test     a  b    echo  DOING TEST   return  a    b

User · Answer

short answer is no  you can t overwrite a function once its in the PHP function scope   your best of using anonymous functions like so   ihatefooexamples   function       return  boo-foo             unset  ihatefooexamples    ihatefooexamples   function        return  really boo-foo       http   php net manual en functions anonymous php

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