《设计模式》（C++）总结

class Shape{
public:
    static Shape * make_shape(int choice);
    virtual void print() = 0; //纯虚函数
};
class Circle:public Shape{/*..*/ };
class Square:public Shape{/*..*/ };
class Rectangle:public Shape{/*..*/ };

Shape * Shape::make_shape(int choice) {
    switch (choice) {
        case 1:
            return new Circle();
        case 2:
            return  new Square();
        case 3:
            return new Rectangle();
    }
}

/*** Factory methods */
static string instConst(string (*inst)(const Reg &target, const Reg &op1, const Value &op2, string comment),
                            const Reg &target, const Reg &op1, const Constant &op2);
static string instConst(string (*inst)(const Reg &target, const Reg &op1, const Reg &op2, string comment),
                            const Reg &target, const Reg &op1, const Constant &op2);
static string instConst(string (*inst)(const Reg &target, const Reg &op1, int imm, string comment),
                            const Reg &target, const Reg &op1, const Constant &op2);
static string instConst(string (*inst)(const Reg &op1, const Value &op2, string comment), const Reg &op1,
                            const Constant &op2);

class LegacyRectangle{
public:
    LegacyRectangle(float x1,float y1,float  x2, float y2){
        m_x1=x1; m_y1=y1; m_x2=x2; m_y2=y2;
    }
    float area(){
        return (m_x2-m_x1)*(m_y2-m_y1);
    }
private:
    float m_x1;
    float m_x2;
    float m_y1;
    float m_y2;
};
class Rectangle{
public:
    virtual float areaSqInch(); //unit:square-inch
};
class RectangleAdapter:public Rectangle,private LegacyRectangle{
public:
    RectangleAdapter(float x,float y,float w,float h): LegacyRectangle(x/39.27f,y/39.37f,(x+w)/39.37f,(y+h)/39.37f){}
    virtual float areaSqInch(){
        float areaSqM = area();
        return areaSqM * 1550.0f;
    }
};