Merge branch 'mediator-pattern'

Mediator/Colleague.php

@@ -0,0 +1,31 @@
+<?php
+
+/*
+ * DesignPatternPHP
+ */
+
+namespace DesignPatterns\Mediator;
+
+/**
+ * Colleague is an abstract colleague who works together but he only knows
+ * the Mediator, not other colleague.
+ */
+abstract class Colleague
+{
+
+    // this ensures no change in subclasses
+    private $mediator;
+
+    // for subclasses
+    protected function getMediator()
+    {
+        return $this->mediator;
+    }
+
+    public function __construct(MediatorInterface $medium)
+    {
+        // in this way, we are sure the concrete colleague knows the mediator
+        $this->mediator = $medium;
+    }
+
+}

Mediator/Mediator.php

@@ -0,0 +1,54 @@
+<?php
+
+/*
+ * DesignPatternPHP
+ */
+
+namespace DesignPatterns\Mediator;
+
+use DesignPatterns\Mediator\Subsystem;
+
+/**
+ * Mediator is the concrete Mediator for this design pattern.
+ * 
+ * This pattern provides an easy to decouple many components working together.
+ * It is a good alternative over Observer IF you have a "central intelligence",
+ * like a controller (but not in the sense of the MVC).
+ * 
+ * All components (called Colleague) are only coupled to the MediatorInterface and
+ * it is a good thing because in OOP, one good friend is better than many. This
+ * is the key-feature of this pattern.
+ * 
+ * In this example, I have made a "Hello World" with the Mediator Pattern, have fun (^_^)
+ */
+class Mediator implements MediatorInterface
+{
+
+    // you could have an array
+    protected $server;
+    protected $database;
+    protected $client;
+
+    public function setColleague(Subsystem\Database $db, Subsystem\Client $cl, Subsystem\Server $srv)
+    {
+        $this->database = $db;
+        $this->server = $srv;
+        $this->client = $cl;
+    }
+
+    public function makeRequest()
+    {
+        $this->server->process();
+    }
+
+    public function queryDb()
+    {
+        return $this->database->getData();
+    }
+
+    public function sendResponse($content)
+    {
+        $this->client->output($content);
+    }
+
+}

Mediator/MediatorInterface.php

@@ -0,0 +1,21 @@
+<?php
+
+/*
+ * DesignPatternPHP
+ */
+
+namespace DesignPatterns\Mediator;
+
+/**
+ * MediatorInterface is a contract for the Mediator
+ * This interface is not mandatory but it is better for LSP concerns
+ */
+interface MediatorInterface
+{
+
+    function sendResponse($content);
+
+    function makeRequest();
+
+    function queryDb();
+}

Mediator/Subsystem/Client.php

@@ -0,0 +1,27 @@
+<?php
+
+/*
+ * DesignPatternPHP
+ */
+
+namespace DesignPatterns\Mediator\Subsystem;
+
+use DesignPatterns\Mediator\Colleague;
+
+/**
+ * Client is a client that make request et get response
+ */
+class Client extends Colleague
+{
+
+    public function request()
+    {
+        $this->getMediator()->makeRequest();
+    }
+
+    public function output($content)
+    {
+        echo $content;
+    }
+
+}

Mediator/Subsystem/Database.php

@@ -0,0 +1,22 @@
+<?php
+
+/*
+ * DesignPatternPHP
+ */
+
+namespace DesignPatterns\Mediator\Subsystem;
+
+use DesignPatterns\Mediator\Colleague;
+
+/**
+ * Database is a database service
+ */
+class Database extends Colleague
+{
+
+    public function getData()
+    {
+        return "World";
+    }
+
+}

Mediator/Subsystem/Server.php

@@ -0,0 +1,23 @@
+<?php
+
+/*
+ * DesignPatternPHP
+ */
+
+namespace DesignPatterns\Mediator\Subsystem;
+
+use DesignPatterns\Mediator\Colleague;
+
+/**
+ * Server serves responses
+ */
+class Server extends Colleague
+{
+
+    public function process()
+    {
+        $data = $this->getMediator()->queryDb();
+        $this->getMediator()->sendResponse("Hello $data");
+    }
+
+}

README.markdown

@@ -23,4 +23,4 @@ Changes I've made :
 * Fixing the Adapter Pattern because it was buggy and incomplete (+ Tests)
 * Adding Template Method Pattern (+ Tests)
 * Adding Builder Pattern (+ Tests)
-* 
+* Adding Mediator Pattern (+ Tests)

Tests/Mediator/MediatorTest.php

@@ -0,0 +1,39 @@
+<?php
+
+/*
+ * DesignPatternPHP
+ */
+
+namespace DesignPatterns\Tests\Mediator;
+
+use DesignPatterns\Mediator\Mediator;
+use DesignPatterns\Mediator\Subsystem\Database;
+use DesignPatterns\Mediator\Subsystem\Client;
+use DesignPatterns\Mediator\Subsystem\Server;
+
+/**
+ * MediatorTest tests hello world
+ */
+class MediatorTest extends \PHPUnit_Framework_TestCase
+{
+
+    protected $client;
+
+    protected function setUp()
+    {
+        $media = new Mediator();
+        $this->client = new Client($media);
+        $media->setColleague(new Database($media), $this->client, new Server($media));
+    }
+
+    public function testOutputHelloWorld()
+    {
+        // testing if Hello World is output :
+        $this->expectOutputString('Hello World');
+        // as you see, the 3 components Client, Server and Database are totally decoupled
+        $this->client->request();
+        // Anyway, it remains complexity in the Mediator that's why the pattern
+        // Observer is preferable in mnay situations.
+    }
+
+}