override_function

Description

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

Syntax similar to create_function(). Overrides built-in functions (replaces them in the symbol table).

例子 1. override_function() example
<?php override_function('test', '$a,$b', 'echo "DOING TEST"; return $a * $b;'); ?>

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rojaro at gmail dot com
21-Sep-2005 03:13


Since Apache 1 & 2 use diffrent methods (Unicode vs. UTF8) on Win32 platforms to encode urls, i've implemented the following workaround to get around this "bug" (which is actually known behaviour and wont get fixed). This workaround is really usefull when writing PHP scripts which have to work on all platforms (Windows, Linux, BSD etc.), must process URLs and must work under both Apache versions.



<?php

$httpd = explode(' ', $_SERVER['SERVER_SOFTWARE']);

if(substr($httpd[0], 0, 6)=='Apache' && substr($httpd[0], 7, 1)==2 && $httpd[1]=='(Win32)')

{

  if(isset($_SERVER['REQUEST_URI'])) $_SERVER['REQUEST_URI'] = str_replace('%2F', '/', rawurlencode(utf8_decode(rawurldecode($_SERVER['REQUEST_URI']))));

  if(isset($_SERVER['REDIRECT_URL'])) $_SERVER['REDIRECT_URL'] = str_replace('%2F', '/', rawurlencode(utf8_decode(rawurldecode($_SERVER['REDIRECT_URL']))));

  override_function('urlencode', '$url', 'return str_replace("%2F", "/", rawurlencode(utf8_encode($url)));');

}

?>

php at undeen dot com
11-Mar-2005 04:07


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.

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