88 - Added undo example for command pattern

Behavioral/Command/Receiver.php

@@ -7,11 +7,40 @@ namespace DesignPatterns\Behavioral\Command;
  */
 class Receiver
 {
+    private $enableDate = false;
+
+    private $output = array();
+
     /**
      * @param string $str
      */
     public function write($str)
     {
-        echo $str;
+        if ($this->enableDate) {
+            $str .= ' ['.date('Y-m-d').']';
+        }
+
+        $this->output[] = $str;
+    }
+
+    public function getOutput()
+    {
+        return implode("\n", $this->output);
+    }
+
+    /**
+     * Enable receiver to display message date.
+     */
+    public function enableDate()
+    {
+        $this->enableDate = true;
+    }
+
+    /**
+     * Disable receiver to display message date.
+     */
+    public function disableDate()
+    {
+        $this->enableDate = false;
     }
 }