1.意图
动态地给一个对象添加一些额外的职责。就增加功能来说，Decorator模式相比生成子类更为灵活。
2.别名
包装器 Wrapper.
3.动机
给某个对象而不是整个类添加一些功能。一个较为灵活的方式时将组件嵌入另一个对象中。
4.适用性
5.结构
6.代码实例
#include <memory>
class Component
{
public:
virtual void Operation()=0;
};
class ConcreteComponent : public Component
{
public:
void Operation();
};
class Decorator : public Component
{
public:
virtual void Operation();
void SetComponent(std::shared_ptr<Component> pComponent);
protected:
std::shared_ptr<Component> m_pComponent;
};
class ConcreteDecoratorA : public Decorator
{
public:
void Operation();
void OtherBehavior();
};
class ConcreteDecoratorB : public Decorator
{
public:
void Operation();
void OtherBehavior();
};
#include "Component.h"
#include <iostream>
void ConcreteComponent::Operation()
{
std::cout << "ConcreteComponent Operation executed" <<std::endl;
}
void Decorator::Operation()
{
m_pComponent->Operation();
}
void Decorator::SetComponent(std::shared_ptr<Component> pComponent)
{
m_pComponent = pComponent;
}
void ConcreteDecoratorA::Operation()
{
Decorator::Operation();
OtherBehavior();
}
void ConcreteDecoratorA::OtherBehavior()
{
std::cout<<"ConceteDecoratorA OtherBehavior executed" << std::endl;
}
void ConcreteDecoratorB::Operation()
{
Decorator::Operation();
OtherBehavior();
}
void ConcreteDecoratorB::OtherBehavior()
{
std::cout<<"ConcreteDecoratorB OtherBehavior executed" << std::endl;
}
#include "Component.h"
int main()
{
std::shared_ptr<Component> pComponent(new ConcreteComponent);
std::shared_ptr<Decorator> pDecoratorA(new ConcreteDecoratorA);
pDecoratorA->SetComponent(pComponent);
pDecoratorA->Operation();
std::shared_ptr<Decorator> pDecoratorB(new ConcreteDecoratorB);
pDecoratorB->SetComponent(pComponent);
pDecoratorB->Operation();
while(1);
}
7.测试结果
8.效果
原文：http://www.cnblogs.com/zhengxingpeng/p/6686296.html