added facade composite and adapter

Adapter/Adapter.php

@@ -0,0 +1,37 @@
+<?php
+
+namespace DesignPatterns;
+
+/**
+ * adapter pattern
+ *
+ * Purpose:
+ * to link two systems, that have different interfaces. An adapter defines interfaces that are equal for all linked
+ * systems and wrap functionality
+ *
+ * Examples:
+ * - different databases have the same interface to communicate although the underlying systems act differently
+ * 
+ * this is a VERY basic example which won't work at all
+ */
+interface DatabaseAdapter
+{
+    public function getTables();
+}
+
+class MySQL implements DatabaseAdapter
+{
+    public function getTables()
+    {
+        return $this->select('SHOW TABLES');
+    }
+}
+
+class SQLite implements DatabaseAdapter
+{
+    public function getTables()
+    {
+        return system('sqlite --list-tables');
+    }
+}
+

Composite/Composite.php

@@ -0,0 +1,68 @@
+<?php
+
+namespace DesignPatterns;
+
+/**
+ * composite pattern
+ *
+ * Purpose:
+ * to treat a group of objects the same way as a single instance of the object
+ *
+ * Example:
+ * - a form class instance handles all its form elements like a single instance of the form, when render() is called, it
+ *      subsequently runs trough all its child elements and calls render() on them
+ *
+ */
+class Form
+{
+    protected $_elements;
+
+    /**
+     * runs through all elements and calls render() on them, then returns the complete representation
+     * of the form
+     *
+     * from the outside, one will not see this and the form will act like a single object instance
+     *
+     * @return string
+     */
+    public function render()
+    {
+        $formCode = '';
+        foreach ($this->_elements as $element) {
+            $formCode .= $element->render();
+        }
+
+        return $formCode;
+    }
+
+    public function addElement(FormElement $element)
+    {
+        $this->_elements[] = $element;
+    }
+}
+
+abstract class FormElement
+{
+    abstract public function render();
+}
+
+class TextElement extends FormElement
+{
+    public function render()
+    {
+        return 'this is a text element';
+    }
+}
+
+class InputElement extends FormElement
+{
+    public function render()
+    {
+        return '<input type="text" />';
+    }
+}
+
+$form = new Form();
+$form->addElement(new TextElement());
+$form->addElement(new InputElement());
+echo $form->render();

Facade/Facade.php

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+<?php
+
+namespace DesignPatterns;
+
+/**
+ * facade pattern
+ *
+ * Purpose:
+ * like a real facade, to hide complexity behind the wall
+ *
+ * Examples:
+ *  - Database Abstraction Layers
+ *
+ */
+class Facade
+{
+    private $_text;
+    private $_queryBuilder;
+
+    public function __construct($text)
+    {
+        $text .= ', called ' . __METHOD__ . ' and thought that would be fairly easy, but ...';
+        $this->_text = $text;
+
+        $this->_initQueryBuilder($text);
+    }
+
+    protected function _initQueryBuilder($sql)
+    {
+        $query = new QueryBuilder();
+        $query->setSql($sql);
+        $this->_queryBuilder = $query;
+    }
+}
+
+class QueryBuilder
+{
+    protected $_sql;
+
+    public function setSql($sql)
+    {
+        $this->_sql = $sql;
+    }
+}
+
+// this is just a simple call, but behind the facade, there's much more going on
+$foo = new Facade('very simple');