more abstract example

Facade/Computer.php

@@ -0,0 +1,52 @@
+<?php
+
+/*
+ * DesignPatternPHP
+ */
+
+namespace DesignPatterns\Facade;
+
+/**
+ * The primary goal of a Facade Pattern is not to avoid you to read the manual of
+ * a complex API. It's only a side-effect.
+ * 
+ * The first goal is to reduce coupling and folow the Law of Demeter.
+ * 
+ * A Facade is meant to decouple a client and a sub-system with
+ * many (but sometimes just one) interface, and of course to reduce complexity.
+ * 
+ * 1. A facade does not forbid you the access to the sub-system
+ * 2. You can (you shoud) have multiple facades for one sub-system
+ * 
+ * That's why a good facade has no "new" in it. If there are multiple creations
+ * for each method, it is not a Facade, it's a Builder or a 
+ * [Abstract|Static|Simple] Factory [Method]
+ *
+ * The best facade has no new and a constructor with interface-type-hinted parameters
+ */
+class Computer
+{
+
+    protected $opsys;
+    protected $bios;
+
+    public function __construct(BiosInterface $bios, OsInterface $os)
+    {
+        $this->bios = $bios;
+        $this->opsys = $os;
+    }
+
+    public function turnOn()
+    {
+        $this->bios->execute();
+        $this->bios->waitForKeyPress();
+        $this->bios->launch($this->opsys);
+    }
+
+    public function turnOff()
+    {
+        $this->opsys->halt();
+        $this->bios->powerDown();
+    }
+
+}