Added simple factory example source code.

examples/creational/simple_factory.cpp

@@ -0,0 +1,63 @@
+#include <iostream>
+#include <memory>
+
+class Door
+{
+  public:
+    typedef std::shared_ptr<Door> ptr_t;
+    virtual float getWidth(void) = 0;
+    virtual float getHeight(void) = 0;
+};
+
+class WoodenDoor : public Door
+{
+  public:
+    WoodenDoor(float width, float height)
+        : width_(width), height_(height)
+    {
+    }
+
+    float getWidth(void)
+    {
+      return width_;
+    }
+
+    float getHeight(void)
+    {
+      return height_;
+    }
+
+  private:
+    float width_;
+    float height_;
+};
+
+class DoorFactory
+{
+  public:
+    static Door::ptr_t makeDoor(float width, float height)
+    {
+      return std::make_shared<WoodenDoor>(width, height);
+    }
+};
+
+int main()
+{
+  // Make a door with dimensions 100x200.
+  Door::ptr_t door = DoorFactory::makeDoor(100, 200);
+
+  // Output: width = 100
+  std::cout << "width = " << door->getWidth() << std::endl;
+  // Output: height = 200
+  std::cout << "height = " << door->getHeight() << std::endl;
+
+  // We can use the factory again to make a door with dimensions 50x100.
+  Door::ptr_t door2 = DoorFactory::makeDoor(50, 100);
+
+  // Output: width = 50
+  std::cout << "width = " << door2->getWidth() << std::endl;
+  // Output: height = 100
+  std::cout << "height = " << door2->getHeight() << std::endl;
+
+  return 0;
+}