callerProxy.php

callerProxy.php

<?php
/** 
 * Caller Proxy Pattern
 * author: phillip@dornauer.cc
 **/


class callerProxyException extends Exception{}

interface iCallerProxy{
	public static function add( $name, $proxy );
	public static function rename( $name, $proxy );
	public static function remove( $name );
	public static function checkPassthrough( );
}

class callerProxy implements iCallerProxy{
	
	private static $proxies = array();
	
	private function __construct(){}
	private function __clone(){}
	
	public static function add( $name, $proxy ){
		if( ! self::$proxies[ $name ] )
			self::_add( $name, $proxy );
		else
			return self::_error( "Proxy '$name' already exists" );
	}
	public static function remove( $name ){
		if( self::$proxies[ $name ] ){
			unset( self::$proxies[ $name ] );
			return true;
		}
		return false;
	}
	public static function rename( $name, $proxy ){
		if( self::$proxies[ $name ] ){
			self::$proxies[ $name ] = $proxy;
			return true;
		}
		return false;
	}
	
	private static function _add( $name, $proxy, $rename = false ){
		self::$proxies[ $name ] = $proxy;
		if( function_exists( $name ) )
			return self::_error( "Function '$name' already exists" );
		
		if( ctype_alpha( $name ) )
			eval( "function $name(){ callerProxy::__passThrough(); }");
		else
			return self::_error( "Invalid Function Name '$name' ");
	}
	
	
	public static function __passThrough(){
		$trace = debug_backtrace();
		$call = $trace[1];
		
		if( self::$proxies[ $call[ "function" ] ] )
			call_user_func_array( self::$proxies[ $call[ "function" ] ], $call[ "args" ] );
		else
			return self::_error( "Function '{$call["function"]}' does not exist" );
	}
	
	public static function checkPassthrough(){
		$trace = debug_backtrace();
		
		if( $trace[ 3 ][ "function" ] != "__passThrough" )
			return self::_error( "Invalid Function Call" );
		
		return true;
	}
	
	
	private static function _error( $message ){
		throw new callerProxyException( $message );
		return false;
	}
}

/***************************************************
*                      usage                       *
***************************************************/


function orginal_test( $name ){
	callerProxy::checkPassthrough();	
	
	echo "name: $name<br />";
}


function another_test( $name ){
	callerProxy::checkPassthrough();	
	
	echo "another name: $name<br />";
}



/* add Proxy
 ***************************************************/
callerProxy::add( "Test", "orginal_test" );

Test( "test" );


/* rename Proxy
 ***************************************************/
callerProxy::rename( "Test", "another_test" );

Test( "another test" );


/* remove Proxy
 ***************************************************/
callerProxy::remove( "Test" );

try{
	Test( "another test" );
}catch( callerProxyException $e ){
	echo "something went wrong: <b>" . $e->getMessage() . "</b><br />";
}