add Abstract Factory

abstract-factory/AbstractFactory.cpp

@@ -0,0 +1,121 @@
+/*
+ * C++ Design Patterns: Abstract Factory
+ * Author: Jakub Vojvoda [github.com/JakubVojvoda]
+ * 2016
+ *
+ * Source code is licenced under MIT licence
+ * (for more details see LICENCE)
+ * 
+ */
+
+#include <iostream>
+
+/*
+ * Product A
+ * products implement the same interface so that the classes can refer
+ * to the interface not the concrete product
+ */
+class ProductA {
+public:
+  virtual std::string getName() = 0;
+  // ...
+};
+
+/*
+ * ConcreteProductAX and ConcreteProductAY
+ * define objects to be created by concrete factory
+ */
+class ConcreteProductAX : public ProductA {
+public:
+  std::string getName() {
+    return "A - X";
+  }
+  // ...
+};
+
+class ConcreteProductAY : public ProductA {
+  std::string getName() {
+    return "A - Y";
+  }
+  // ...
+};
+
+/*
+ * Product B
+ * same as Product A, Product B declares interface for concrete products
+ * where each can produce an entire set of products
+ */
+class ProductB {
+public:
+  virtual std::string getName() = 0;
+  // ...
+};
+
+/*
+ * ConcreteProductBX and ConcreteProductBY
+ * same as previous concrete product classes
+ */
+class ConcreteProductBX : public ProductB {
+  std::string getName() {
+    return "B - X";
+  }
+  // ...
+};
+
+class ConcreteProductBY : public ProductB {
+  std::string getName() {
+    return "B - Y";
+  }
+  // ...
+};
+
+/*
+ * Abstract Factory
+ * provides an abstract interface for creating a family of products
+ */
+class AbstractFactory {
+public:
+  virtual ProductA *createProductA() = 0;
+  virtual ProductB *createProductB() = 0;
+};
+
+/*
+ * Concrete Factory X and Y
+ * each concrete factory create a family of products and client uses
+ * one of these factories so it never has to instantiate a product object
+ */
+class ConcreteFactoryX : public AbstractFactory {
+public:
+  ProductA *createProductA() {
+    return new ConcreteProductAX();
+  }
+  ProductB *createProductB() {
+    return new ConcreteProductBX();
+  }
+  // ...
+};
+
+class ConcreteFactoryY : public AbstractFactory {
+public:
+  ProductA *createProductA() {
+    return new ConcreteProductAY();
+  }
+  ProductB *createProductB() {
+    return new ConcreteProductBY();
+  }
+  // ...
+};
+
+
+int main()
+{
+    ConcreteFactoryX *factoryX = new ConcreteFactoryX();
+    ConcreteFactoryY *factoryY = new ConcreteFactoryY();
+
+    ProductA *p1 = factoryX->createProductA();
+    std::cout << "Product: " << p1->getName() << std::endl;
+
+    ProductA *p2 = factoryY->createProductA();
+    std::cout << "Product: " << p2->getName() << std::endl;
+
+}