abstract factory sample c++ code

The following is an example of abstract factory Design Pattern tested on RHEL 5 with gcc 4.1.2. 

The program will also work on visual studio with little or no modifications.

/*

 * File         :    abstract_factory.cpp

 * Note         :    uncomment the SIMPLE or ROBUST to use

 */

#include <iostream>

//#define SIMPLE     1

#define ROBUST  2

using namespace std;

class Shape {

  public:

    Shape() {

      id_ = total_++;

    }

    virtual void draw() = 0;

  protected:

    int id_;

    static int total_;

};

int Shape::total_ = 0;

class Circle : public Shape {

  public:

    void draw() {

      cout << "circle " << id_ << ": draw" << endl;

    }

};

class Square : public Shape {

  public:

    void draw() {

      cout << "square " << id_ << ": draw" << endl;

    }

};

class Ellipse : public Shape {

  public:

    void draw() {

      cout << "ellipse " << id_ << ": draw" << endl;

    }

};

class Rectangle : public Shape {

  public:

    void draw() {

      cout << "rectangle " << id_ << ": draw" << endl;

    }

};

class Factory {

  public:

    virtual Shape* createCurvedInstance() = 0;

    virtual Shape* createStraightInstance() = 0;

};

class SimpleShapeFactory : public Factory {

  public:

    Shape* createCurvedInstance() {

      return new Circle;

    }

    Shape* createStraightInstance() {

      return new Square;

    }

};

class RobustShapeFactory : public Factory {

  public:

    Shape* createCurvedInstance()   {

      return new Ellipse;

    }

    Shape* createStraightInstance() {

      return new Rectangle;

    }

};

int main() {

#ifdef SIMPLE

  Factory* factory = new SimpleShapeFactory;

#elif ROBUST

  Factory* factory = new RobustShapeFactory;

#endif

  Shape* shapes[3];

  shapes[0] = factory->createCurvedInstance();   // shapes[0] = new Ellipse;

  shapes[1] = factory->createStraightInstance(); // shapes[1] = new Rectangle;

  shapes[2] = factory->createCurvedInstance();   // shapes[2] = new Ellipse;

  for (int i=0; i < 3; i++) {

    shapes[i]->draw();

  }

}

/*
[sgupta@rhel55x86 abstract_factory]$ ./abstract_factory

ellipse 0: draw

rectangle 1: draw

ellipse 2: draw
[sgupta@rhel55x86 abstract_factory]$

*/