override_function()

(PECL apd >= 0.2)

Overrides built-in functions

说明

override_function(string $function_name,string $function_args,string $function_code): bool

Overrides built-in functions by replacing them in the symbol table.

参数

$function_name

The function to override.

$function_args

The function arguments, as a comma separated string.

Usually you will want to pass this parameter, as well as the$function_codeparameter, as a single quote delimited string. The reason for using single quoted strings, is to protect the variable names from parsing, otherwise, if you use double quotes there will be a need to escape the variable names, e.g.$your_var.

$function_code

The new code for the function.

返回值

成功时返回TRUE，或者在失败时返回FALSE。

范例

Example #1 override_function() example

<?php
override_function('test', '$a,$b', 'echo "DOING TEST"; return $a * $b;');
?>

I thought the example was not very helpful, because it doesn't even override the function with another function.
My question was: If I override a function, can I call the ORIGINAL function within the OVERRIDING function?
ie, can I do this:
<?php
override_function('strlen', '$string', 'return override_strlen($string);');
function override_strlen($string){
    return strlen($string); 
}
?>
The answer: NO, you will get a segfault.
HOWEVER, if you use rename_function to rename the original function to a third name, then call the third name in the OVERRIDING function, you will get the desired effect:
<?php
rename_function('strlen', 'new_strlen');
override_function('strlen', '$string', 'return override_strlen($string);');
function override_strlen($string){
    return new_strlen($string); 
}
?>
I plan to use this functionality to generate log reports every time a function is called, with the parameters, time, result, etc... So to wrap a function in logging, that was what I had to do.

Overriden function name becomes __overridden__(). That's why you can't override two function, and that's how you can use the original function in the override.

Of course you can't overwrite "functions" like require_once or print as they are not really a function but a language construct.

You can find Excepción - Call to undefined function override_function()
due to Function override_function is part of PECL Extension.
Configure PECL

Please note that this function (as of v1.0.1 in PHP 5.3) will <b>not</b> override some important built-in "functions". Specifically, those which are actually statements/keywords, such as:
  require
  include
  require_once
  include_once
  echo
  print
I was hoping to use it to trace the chains of require/include activity among files in a large legacy project, but it seems APD will not do what I need.

Yes you can if you rename the overridden function. So you first rename original function, then override it and finally rename the overridden one, something like this:
rename_function('feof', 'real_feof');
override_function('feof', '$handle', 'return true;');
rename_function("__overridden__", 'dummy_feof');

There is not chance to override 2 or more functions, because of the error:
Fatal error: Cannot redeclare __overridden__()

Maybe it's better to use overwritten function inside the override to code something like this :
<?php
rename_function('myFunction','original_myFunction');
override_function('myFunction','$arg,…,$argN','return override_myFunction($arg,…,$argN);');
?>
You may then give somehow "inheritance" to override_myFunction …
As a parent :
<?php
function override_myFunction($arg,…,$argN)
{  $result=original_myFunction($arg,…,$argN));
   /* CODE that manipulates the result */
   return $result;
}
?>
As a child :
<?php
function override_myFunction($arg,…,$argN)
{  /* CODE that manipulates the arguments */
   return original_myFunction($arg,…,$argN));
}
?>