C++设计模式：装饰器模式

一、源代码：

#include<iostream>
#include<memory>

using namespace std;

class Shape
{
public:
    virtual void draw() = 0;
    virtual ~Shape() = default;
};

class Rectangle:public Shape
{
public:
    virtual void draw() override
    {
        cout<<"Shape:Rectangle"<<endl;
    }
};

class Circle:public Shape
{
public:
    virtual void draw() override
    {
        cout<<"Shape:Circle"<<endl;
    }
};

class ShapeDecorator:public Shape
{
public:
    ShapeDecorator(shared_ptr<Shape> decoratodShape)
    {
        this->_decoratedShape = decoratodShape;
    }
    virtual void draw() override
    {
        _decoratedShape->draw();
    }
protected:
    shared_ptr<Shape> _decoratedShape;
};

class RedShapeDecorator:public ShapeDecorator
{
public:
    RedShapeDecorator(shared_ptr<Shape> decoratedShape):ShapeDecorator(decoratedShape)
    {}

    virtual void draw() override
    {
        _decoratedShape->draw();
        setRedBorder();
    }
private:
    void setRedBorder()
    {
        cout<<"Border Color:Red"<<endl;
    }
};

int main()
{
    shared_ptr<Shape> circle = make_shared<Circle>();
    shared_ptr<Shape> redCircle = make_shared<RedShapeDecorator>(make_shared<Circle>());
    shared_ptr<Shape> redRectangle = make_shared<RedShapeDecorator>(make_shared<Rectangle>());

    cout<<"Circle with normal border"<<endl;
    circle->draw();
    cout<<"\nCircle of red border"<<endl;
    redCircle->draw();
    cout<<"\nRectangle of red border"<<endl;
    redRectangle->draw();
}

二、运行结果：