Override PHP Function

PHP have PECL (PHP Extension & Community Library) function to override built-in functions by replacing them in the symbol table.

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

1. <?php
2. override_function(‘strlen’, ‘$string’, ‘return override_strlen($string);’);
3. function override_strlen($string){
4. return strlen($string);
5. }
6. ?>

The above function “override_function()” require APD i.e. Advanced PHP Debugger.

We can find more about APD here…
http://pecl.php.net/package/apd

Linux users can install apd using below command

# pecl install apd

There is an alternate way to override PHP functions, we can use below class “override” to override any built-in PHP function if PECL is not installed on server

1. <?php
2. $or = new override ();
3. $or->override_function(‘strlen’, ‘override_strlen‘, ‘return override_strlen($string);’);
4. function override_strlen($string){
5. return strlen($string);
6. }
7. ?>
   
   

<?php

$url = 'http://www.svnlabs.com';
$override = new override();

$override->override_function('file_get_contents','fileGetContents',$url);

if ($over_func_name = $override->override_check('file_get_contents')) {
    $result=call_user_func($over_func_name, $url);
}


function fileGetContents($url)
{
  /// statements
}

?>

PHP Function OverRide Class
 


<?php


class override {


var $functions = array();


var $includes = array();


function override_function($override, $function, $include) {


if ($include) {


$this->includes[$override] = $include;


}


else if (isset($this->includes[$override])) {


unset($this->includes[$override]);


}


$this->functions[$override] = $function;


}


function override_check($override) {


if (isset($this->includes[$override])) {


if (file_exists($this->includes[$override])) {


include_once($this->includes[$override]);


}


if (function_exists($this->functions[$override])) {


return $this->functions[$override];


} else {


return false;


}


} else {


return false;


}


}


}


?>


 
 
 
 
Make a habit of creating things modular, that means “pluggable” and “unpluggable”. 
 
<?php
class override {
var $functions = array();
var $includes = array();
function override_function($override, $function, $include) {
if ($include) {
$this->includes[$override] = $include;
}
else if (isset($this->includes[$override])) {
unset($this->includes[$override]);
}
$this->functions[$override] = $function;
}
function override_check($override) {
if (isset($this->includes[$override])) {
if (file_exists($this->includes[$override])) {
include_once($this->includes[$override]);
}
if (function_exists($this->functions[$override])) {
return $this->functions[$override];
} else {
return false;
}
} else {
return false;
}
}
}
?>





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