#include <iostream>
using namespace std;
// Abstract Shape
struct Shape { virtual ~Shape(){} };
enum {SHAPE_LINE = 1, SHAPE_POLYGON = 3, SHAPE_CIRCLE = 5};
// Concrete Shapes: Line, Polygon and Circle
struct Line : public Shape {
Line() { cout << "Line::ctor" << endl; }
};
struct Polygon : public Shape {
Polygon() { cout << "Polygon::ctor" << endl; }
};
struct Circle : public Shape {
Circle() { cout << "Circle::ctor" << endl; }
};
// Comment out the line below if you want to use traditional method
#define USE_LOKI
#ifndef USE_LOKI // traditional method
class ShapeFactory {
public:
static ShapeFactory& Instance() {
static ShapeFactory instance;
return instance;
}
Shape* CreateObject(int id){
switch(id) {
case SHAPE_LINE:
return new Line;
case SHAPE_POLYGON:
return new Polygon;
case SHAPE_CIRCLE:
return new Circle;
default:
throw "Unknown Type";
}
}
protected:
ShapeFactory() {}
private:
ShapeFactory(const ShapeFactory&);
ShapeFactory& operator=(const ShapeFactory&);
};
#else // Loki method
#include "Factory.h"
#include "Singleton.h"
using namespace Loki;
typedef SingletonHolder<Factory<Shape, int> > ShapeFactory;
Shape* CreateLine(){return new Line;}
static const bool lineReg = ShapeFactory::Instance().Register(SHAPE_LINE, CreateLine);
Shape* CreatePolygon(){return new Polygon;}
static const bool polygonReg = ShapeFactory::Instance().Register(SHAPE_POLYGON, CreatePolygon);
Shape* CreateCircle(){return new Circle;}
static const bool circleReg = ShapeFactory::Instance().Register(SHAPE_CIRCLE, CreateCircle);
#endif
void main()
{
int id[3] = {SHAPE_LINE, SHAPE_POLYGON, SHAPE_CIRCLE};
Shape* pShapes[3];
for(int i = 0; i < 3; i++){
pShapes[i] = ShapeFactory::Instance().CreateObject(id[i]);
delete pShapes[i];
}
}
