start a restructure

Creational/Singleton/README.md

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+# Singleton
+
+**THIS IS CONSIDERED TO BE AN ANTI-PATTERN! FOR BETTER TESTABILITY AND MAINTAINABILITY USE DEPENDENCY INJECTION!**
+
+## Purpose
+
+To have only one instance of this object in the application that will handle all calls.
+
+## Examples
+
+* DB Connector
+* Logger (may also be a Multiton if there are many log files for several purposes)
+* Lock file for the application (there is only one in the filesystem ...)
+
+## Diagram
+
+<img src="http://yuml.me/diagram/scruffy/class/[Singleton|-instance: Singleton|+getInstance(): Singleton;-__construct(): void;-__clone(): void;-__wakeup(): void]" >

Creational/Singleton/Singleton.php

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+<?php
+
+namespace DesignPatterns\Singleton;
+
+/**
+ * class Singleton
+ */
+class Singleton
+{
+    /**
+     * @var cached reference to singleton instance 
+     */
+    protected static $instance;
+    
+    /**
+     * gets the instance via lazy initialization (created on first usage)
+     *
+     * @return self
+     */
+    public static function getInstance()
+    {
+        
+        if (null === static::$instance) {
+            static::$instance = new static;
+        }
+
+        return static::$instance;
+    }
+
+    /**
+     * is not allowed to call from outside: private!
+     *
+     */
+    private function __construct()
+    {
+
+    }
+
+    /**
+     * prevent the instance from being cloned
+     *
+     * @return void
+     */
+    private function __clone()
+    {
+
+    }
+
+    /**
+     * prevent from being unserialized
+     *
+     * @return void
+     */
+    private function __wakeup()
+    {
+
+    }
+}

Creational/Singleton/Test/SingletonTest.php

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+<?php
+
+namespace DesignPatterns\Tests\Singleton;
+
+use DesignPatterns\Singleton\Singleton;
+
+/**
+ * SingletonTest tests the singleton pattern
+ */
+class SingletonTest extends \PHPUnit_Framework_TestCase
+{
+
+    public function testUniqueness()
+    {
+        $firstCall = Singleton::getInstance();
+        $this->assertInstanceOf('DesignPatterns\Singleton\Singleton', $firstCall);
+        $secondCall = Singleton::getInstance();
+        $this->assertSame($firstCall, $secondCall);
+    }
+
+    public function testNoConstructor()
+    {
+        $obj = Singleton::getInstance();
+
+        $refl = new \ReflectionObject($obj);
+        $meth = $refl->getMethod('__construct');
+        $this->assertTrue($meth->isPrivate());
+    }
+}