<?php
/**
* File containing the ezcBaseInit class.
*
* @package Base
* @version 1.8
* @copyright Copyright (C) 2005-2009 eZ Systems AS. All rights reserved.
* @license http://ez.no/licenses/new_bsd New BSD License
*/
/**
* Provides a method to implement delayed initialization of objects.
*
* With the methods in this class you can implement callbacks to configure
* singleton classes. In order to do so you will have to change the
* getInstance() method of your singleton class to include a call to
* ezcBaseInit::fetchConfig() as in the following example:
*
* <code>
* <?php
* public static function getInstance()
* {
* if ( is_null( self::$instance ) )
* {
* self::$instance = new ezcConfigurationmanager();
* ezcBaseInit::fetchConfig( 'ezcInitConfigurationManager', self::$instance );
* }
* return self::$instance;
* }
* ?>
* </code>
*
* You will also need to configure which callback class to call. This you do
* with the ezcBaseInit::setCallback() method. The following examples sets the
* callback classname for the configuration identifier
* 'ezcInitConfigurationManager' to 'cfgConfigurationManager':
*
* <code>
* <?php
* ezcBaseInit::setCallback( 'ezcInitConfigurationManager', 'cfgConfigurationManager' );
* ?>
* </code>
*
* The class 'cfgConfigurationManager' is required to implement the
* ezcBaseConfigurationInitializer interface, which defines only one method:
* configureObject(). An example on how to implement such a class could be:
*
* <code>
* <?php
* class cfgConfigurationManager implements ezcBaseConfigurationInitializer
* {
* static public function configureObject( ezcConfigurationManager $cfgManagerObject )
* {
* $cfgManagerObject->init( 'ezcConfigurationIniReader', 'settings', array( 'useComments' => true ) );
* }
* }
* ?>
* </code>
*
* Of course the implementation of this callback class is up to the application
* developer that uses the component (in this example the Configuration
* component's class ezcConfigurationManager).
*
* @package Base
* @version 1.8
*/
class ezcBaseInit
{
/**
* Contains the callback where the identifier is the key of the array, and the classname to callback to the value.
*
* @var array(string=>string)
*/
static private $callbackMap = array();
/**
* Adds the classname $callbackClassname as callback for the identifier $identifier.
*
* @param string $identifier
* @param string $callbackClassname
*/
public static function setCallback( $identifier, $callbackClassname )
{
if ( array_key_exists( $identifier, self::$callbackMap ) )
{
throw new ezcBaseInitCallbackConfiguredException( $identifier, self::$callbackMap[$identifier] );
}
else
{
// Check if the passed classname actually exists
if ( !ezcBaseFeatures::classExists( $callbackClassname, true ) )
{
throw new ezcBaseInitInvalidCallbackClassException( $callbackClassname );
}
// Check if the passed classname actually implements the interface.
if ( !in_array( 'ezcBaseConfigurationInitializer', class_implements( $callbackClassname ) ) )
{
throw new ezcBaseInitInvalidCallbackClassException( $callbackClassname );
}
self::$callbackMap[$identifier] = $callbackClassname;
}
}
/**
* Uses the configured callback belonging to $identifier to configure the $object.
*
* The method will return the return value of the callback method, or null
* in case there was no callback set for the specified $identifier.
*
* @param string $identifier
* @param object $object
* @return mixed
*/
public static function fetchConfig( $identifier, $object )
{
if ( isset( self::$callbackMap[$identifier] ) )
{
$callbackClassname = self::$callbackMap[$identifier];
return call_user_func( array( $callbackClassname, 'configureObject' ), $object );
}
return null;
}
}
?>
