cs

ChainOfResponsibilities/ChainOfResponsibilities.php

@@ -1,96 +0,0 @@
-<?php
-
-namespace DesignPatterns;
-
-/**
- * chain of responsibilities pattern
- *
- * Purpose:
- * to build a chain of objects to handle a call. if one object cannot handle a call, it delegates the call to the next
- * in the chain and so forth
- *
- * Examples:
- * - logging framework
- * - spam filter
- * - Caching: first object is an instance of e.g. a Memcached Interface, if that "misses" it delegates the call to the
- *   Database Interface
- * - Yii Framework: CFilterChain is a chain of controller action filters. the executing point is passed from one filter
- *   to the next along the chain, and only if all filters say "yes", the action can be invoked at last.
- *
- */
-
-// the idea is good but in general, the Handler component in this pattern 
-// is an abstract class which makes much more of the work
-interface KeyValueStorage
-{
-    public function get($key);
-}
-
-class SlowStorage implements KeyValueStorage
-{
-    protected $_data = array();
-
-    public function __construct($data = array())
-    {
-        $this->_data = $data;
-    }
-
-    /**
-     * this class has no next handler, so it MUST be able to handle all requests
-     *
-     * @param $key
-     * @return mixed
-     */
-    public function get($key)
-    {
-        return $this->_data[$key];
-    }
-}
-
-class FastStorage implements KeyValueStorage
-{
-    /**
-     * @var array
-     */
-    protected $_data;
-
-    /**
-     * the next handler in the chain
-     *
-     * @var \DesignPatterns\KeyValueStorage
-     */
-    protected $_nextHandler;
-
-    public function __construct(array $data, KeyValueStorage $nextHandler)
-    {
-        $this->_data = $data;
-        $this->_nextHandler = $nextHandler;
-    }
-
-    /**
-     * when this storage gets a "miss", search in next handler
-     *
-     * @param $key
-     * @return mixed
-     */
-    public function get($key)
-    {
-        if (true /* miss */) {
-            // delegate the call to the next handler in the chain
-            return $this->_nextHandler->get($key);
-        }
-    }
-}
-
-// BUILD THE STORAGES AND CHAIN
-
-$slowStorage = new SlowStorage(array('foo' => 'bar'));
-$fastStorage = new FastStorage(array('bar' => 'baz'), $slowStorage);
-
-$fastStorage->get('foo'); // will be handled by SlowStorage
-$fastStorage->get('bar'); // will be handled by FastStorage
-
-/**
- * In this example we could also add a abstract class and extend it to build Fast- and SlowStorage. That class would
- * then manage the chain and when the cache hits a "miss", it would check if there is a next handler
- */

ChainOfResponsibilities/README.md

@@ -0,0 +1,13 @@
+# chain of responsibilities
+
+## Purpose:
+
+To build a chain of objects to handle a call. if one object cannot handle a call, it delegates the call to the next
+in the chain and so forth
+
+## Examples:
+
+*  logging framework
+*  spam filter
+  Caching: first object is an instance of e.g. a Memcached Interface, if that "misses" it delegates the call to the database interface
+*  Yii Framework: CFilterChain is a chain of controller action filters. the executing point is passed from one filter to the next along the chain, and only if all filters say "yes", the action can be invoked at last.