decorator pattern.

decorator pattern

1.소스

#include <iostream>

using namespace std;

class I {

public:
    virtual ~I(){}
    virtual void do_it() = 0;
};


class A: public I {

public:
    ~A() {
        cout << "A dtor" << '\n';
    }
	
    /*virtual*/
    void do_it() {
        cout << 'A';
    }
};


class D: public I {

public:
    D(I *inner) {
        m_wrappee = inner;
    }
	
    ~D() {
        delete m_wrappee;
    }
	
    /*virtual*/
    void do_it() {
        m_wrappee->do_it();
    }

private:
    I *m_wrappee;
};

class X: public D {

public:
    X(I *core): D(core){}
	
    ~X() {
        cout << "X dtor" << "   ";
    }
	
    /*virtual*/
    void do_it() {
        D::do_it();
        cout << 'X';
    }
};

class Y: public D {

public:
    Y(I *core): D(core){}
    ~Y() {
        cout << "Y dtor" << "   ";
    }
	
    /*virtual*/
    void do_it() {
        D::do_it();
        cout << 'Y';
    }
};

class Z: public D {

public:
    Z(I *core): D(core){}
    ~Z() {
        cout << "Z dtor" << "   ";
    }
	
    /*virtual*/
    void do_it() {
        D::do_it();
        cout << 'Z';
    }
};

int maint( int argc , char ** argv ) 
{ 

    I *anX = new X(new A);
    I *anXY = new Y(new X(new A));
    I *anXYZ = new Z(new Y(new X(new A)));
	
    anX->do_it();
    cout << '\n';
    anXY->do_it();
    cout << '\n';
    anXYZ->do_it();
    cout << '\n';
    delete anX;
    delete anXY;
    delete anXYZ;
}

2.결과

g++ -o decorator decorator.cpp
hacker@HACKER:~/cpp$ ./decorator
AX
AXY
AXYZ
X dtor   A dtor
Y dtor   X dtor   A dtor
Z dtor   Y dtor   X dtor   A dtor