Chain of responsibility pattern example

ChainOfResponsibility.php

<?php
/*
Chain of Responsibility Pattern - Wiki
---------------------------------------
* In object-oriented design, the chain-of-responsibility pattern is a design pattern consisting of a source of command objects and * a series of processing objects.[1] Each processing object contains logic that defines the types of command objects that it can
* handle; the rest are passed to the next processing object in the chain. A mechanism also exists for adding new processing bjects * to the end of this chain.In a variation of the standard chain-of-responsibility model, some handlers may act as 
* dispatchers,capable of sending commands out in a variety of directions, forming a tree of responsibility. In some cases, this 
* can occur recursively, with processing objects calling higher-up processing objects with commands that attempt to solve some 
* smaller part of the problem; in this case recursion continues until the command is processed, or the entire tree has been 
* explored. An XML interpreter might work in this manner.
*
* This pattern promotes the idea of loose coupling.
*/

//The abstrac Chain
abstract class BookChain{
	private $nextBookChain = null;

	public function getStore($request){}

	public function nextStore(BookChain $nextBookChain){}
	
}

class SyntagmaStore extends BookChain{

	

	public function nextStore(BookChain $next){

		$this->nextBookChain = $next;

	}	
	
	public function getStore($store){

		if($store == "syntagma")
			echo "This is the Syntagma book store\r\n";
		else
			$this->nextBookChain->getStore($store);
	}
}

class SounioStore extends BookChain{

	public function nextStore(BookChain $next){

		$this->nextBookChain = $next;

	}	
	
	public function getStore($store){

		if($store == "sounio")
			echo "This is the Sounio book store\r\n";
		else
			$this->nextBookChain->getStore($store);
	}


}

class OmonoiaStore extends BookChain{

	public function nextStore(BookChain $nextBookChain){

		$this->nextBookChain = $nextBookChain;

	}	
	
	public function getStore($store){

		if($store == "omonoia")
			echo "This is the Omonoia book store\r\n";
		else
			echo "No Store\r\n";
	}
}

//Create instance of everything
$bookStore1 = new SyntagmaStore();
$bookStore2 = new SounioStore();
$bookStore3 = new OmonoiaStore();

//Define the chain
$bookStore1->nextStore($bookStore2);
$bookStore2->nextStore($bookStore3);

// This will run the getStore method of SounioStore
$bookStore1->getStore("sounio");

// This will run the getStore method of SyntagmaStore
$bookStore1->getStore("syntagma");

// This will run the getStore method of OmonoiaStore
$bookStore1->getStore("omonoia");

//When everything fails
$bookStore1->getStore("random strint");

?>