/* 
 * factory.cpp
 *
 * Example of Factory Method
 *
 * Define an interface for creating an object, but
 * let subclasses decide which class to instantiate.
 */

#include <iostream>
#include <string>

class Document {

public:
  virtual void operation() = 0;
};

class DrawingDocument : public Document {

public:
  void operation() { std::cout << "DrawingDocument\n"; }
};

class Application {

public:
  virtual Document* factoryMethod() = 0;

  void operation() { }
};

class DrawingApplication : public Application {

public:
  virtual DrawingDocument* factoryMethod() { return new DrawingDocument; }
};

class Client {

public:
  Client(Application& creator) : _creator(creator) {}

  void dosomething() {
    Document* pproduct = _creator.factoryMethod();

    pproduct->operation();
  }

private:
  Application& _creator;
};

int main() {

  DrawingApplication drawingApplication;

  Client client(drawingApplication);

  client.dosomething();
}