start a restructure

Behavioral/TemplateMethod/Journey.php

@@ -0,0 +1,60 @@
+<?php
+
+namespace DesignPatterns\TemplateMethod;
+
+/**
+ *
+ */
+abstract class Journey
+{
+    /**
+     * This is the public service provided by this class and its subclasses.
+     * Notice it is final to "freeze" the global behavior of algorithm.
+     * If you want to override this contract, make an interface with only takeATrip() 
+     * and subclass it.
+     */
+    final public function takeATrip()
+    {
+        $this->buyAFlight();
+        $this->takePlane();
+        $this->enjoyVacation();
+        $this->buyGift();
+        $this->takePlane();
+    }
+
+    /**
+     * This method must be implemented, this is the key-feature of this pattern
+     */
+    abstract protected function enjoyVacation();
+
+    /**
+     * This method is also part of the algorithm but it is optional.
+     * This is an "adapter" (do not confuse with the Adapter pattern, not related)
+     * You can override it only if you need to.
+     */
+    protected function buyGift()
+    {
+    }
+
+    /**
+     * this method will be unknown by subclasses (better)
+     */
+    private function buyAFlight()
+    {
+        echo "Buying a flight\n";
+    }
+
+    /**
+     * sbclasses will get access to this method but cannot override it and
+     * compromise this algorithm (warning : cause of cyclic dependencies)
+     */
+    final protected function takePlane()
+    {
+        echo "Taking the plane\n";
+    }
+
+    // A note regarding the keyword "final" : don't use it when you start coding :
+    // add it after you narrow and know exactly what change and what remain unchanged
+    // in this algorithm.
+    // [abstract] x [3 access] x [final] = 12 combinations, it can be hard !
+}