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Description

bool spl_autoload_register ( [mixed autoload_function] )

Register a function with the spl provided __autoload stack. If the stack is not yet activated it will be activated. If no parameter is provided the default implementation spl_autoload will be registered. When registering is successful the return value is true and upon failure false is being returned.

If your code has an existing __autoload function then this function must explicitly registered on the __autoload stack. This is because spl_autoload_register() will effectively replace the engine cache for the __autoload function by either spl_autoload() or spl_autoload_call().

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spl_autoload_register

stanlemon at mac dot com
28-Sep-2007 10:20


The spl_autoload_register() method registers functions in its stack in the order that spl_autoload_register() was called, and subsequently if you want an autoload function to override previous autoload functions you will either need to unregister the previous ones or change the order of the autoload stack.



For example, say in your default implementation of an autoload function you throw an exception if the class cannot be found, or perhaps a fatal error.  Later on in your code you add a second implementation of an autoload function which will load a library that the previous method would fail on.  This will not call the second autoloader method first, but rather will continue to error out on the first method.



As previously mentioned, you can unregister the existing autoloader that errors out, or you can create a mechanism for unregistering and re-registering the autoloaders in the order you want.



Here is a sample/example of how you might consider re-registering autoloaders so that the newest autoloader is called first, and the oldest last:



<?php



function spl_autoload_preregister( $autoload ) {

    // No functions currently in the stack.

    if ( ($funcs = spl_autoload_functions()) === false ) {

        spl_autoload_register($func);

    } else {

        // Unregister existing autoloaders...

        foreach ($funcs as $func) {

            spl_autoload_unregister($func);

        }

        

        // Register the new one, thus putting it at the front of the stack...

        spl_autoload_register($autoload);

        

        // Now, go back and re-register all of our old ones.

        foreach ($funcs as $func) {

            spl_autoload_register($func);

        }

    }

}



?>



Note: I have not tested this for overhead, so I am not 100% sure what the performance implication of the above example are.

harvey dot NO_SPAM dot robin at gmail dot com
10-Feb-2007 05:54


This function is smart enough not to add the same loader twice.  This seems to work for all of the different loader formats.  Example:



<?php

class ALoader

{

  static function load($class) { return true; }

}



function anotherLoader($class) {

  return true;

}



$F = new ALoader;



spl_autoload_register(array('ALoader', 'load'));

spl_autoload_register(array('ALoader', 'load'));

spl_autoload_register(array($F, 'load'));

spl_autoload_register('anotherLoader');

spl_autoload_register('anotherLoader');

var_dump(spl_autoload_functions());



/*

 * Results on PHP5.2 CLI, linux.

 * array(2) {

 *  [0]=>

 *  array(2) {

 *    [0]=>

 *    string(7) "ALoader"

 *    [1]=>

 *    string(4) "load"

 *  }

 *  [1]=>

 *  string(13) "anotherLoader"

 * }

 */

?>

florent at mediagonale dot com
14-Nov-2006 01:19


If your autoload function is a class method, you can call spl_autoload_register with an array specifying the class and the method to run.



* You can use a static method :

<?php



class MyClass {

  public static function autoload($className) {

    // ...

  }

}



spl_autoload_register(array('MyClass', 'autoload'));

?>



* Or you can use an instance :

<?php

class MyClass {

  public function autoload($className) {

    // ...

  }

}



$instance = new MyClass();

spl_autoload_register(array($instance, 'autoload'));

?>

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