Added abstract factory example source code.

examples/creational/abstract_factory.cpp

@@ -0,0 +1,107 @@
+#include <iostream>
+#include <memory>
+
+class Door
+{
+  public:
+    typedef std::shared_ptr<Door> ptr_t;
+    virtual void getDescription(void) = 0;
+};
+
+class WoodenDoor : public Door
+{
+  public:
+    void getDescription(void)
+    {
+      std::cout << "I am a wooden door." << std::endl;
+    }
+};
+
+class IronDoor : public Door
+{
+  public:
+    void getDescription(void)
+    {
+      std::cout << "I am an iron door." << std::endl;
+    }
+};
+
+class DoorFittingExpert
+{
+  public:
+    typedef std::shared_ptr<DoorFittingExpert> ptr_t;
+    virtual void getDescription(void) = 0;
+};
+
+class Welder : public DoorFittingExpert
+{
+  public:
+    void getDescription(void)
+    {
+      std::cout << "I can only fit iron doors." << std::endl;
+    }
+};
+
+class Carpenter : public DoorFittingExpert
+{
+  public:
+    void getDescription(void)
+    {
+      std::cout << "I can only fit wooden doors." << std::endl;
+
+    }
+};
+
+class DoorFactory
+{
+  public:
+    virtual Door::ptr_t makeDoor(void) = 0;
+    virtual DoorFittingExpert::ptr_t makeFittingExpert(void) = 0;
+};
+
+class WoodenDoorFactory : public DoorFactory
+{
+  public:
+    Door::ptr_t makeDoor(void)
+    {
+      return std::make_shared<WoodenDoor>();
+    }
+
+    DoorFittingExpert::ptr_t makeFittingExpert(void)
+    {
+      return std::make_shared<Carpenter>();
+    }
+};
+
+class IronDoorFactory : public DoorFactory
+{
+  public:
+    Door::ptr_t makeDoor(void)
+    {
+      return std::make_shared<IronDoor>();
+    }
+
+    DoorFittingExpert::ptr_t makeFittingExpert(void)
+    {
+      return std::make_shared<Welder>();
+    }
+};
+
+int main()
+{
+  WoodenDoorFactory woodenFactory = WoodenDoorFactory();
+  Door::ptr_t door = woodenFactory.makeDoor();
+  DoorFittingExpert::ptr_t expert = woodenFactory.makeFittingExpert();
+
+  door->getDescription(); // Output: I am a wooden door.
+  expert->getDescription(); // Output: I can only fit wooden doors.
+
+  IronDoorFactory ironFactory = IronDoorFactory();
+  Door::ptr_t door2 = ironFactory.makeDoor();
+  DoorFittingExpert::ptr_t expert2 = woodenFactory.makeFittingExpert();
+
+  door2->getDescription(); // Output: I am an iron door.
+  expert2->getDescription(); // Output: I can only fit iron doors.
+
+  return 0;
+}