设计模式-装饰模式

来源：互联网发布：期货软件app 编辑：程序博客网时间：2024/05/29 07:35

适用情境:给一个类添加一些额外的功能,而不修改原来类的代码.添加的功能一般不是非常重要的核心功能,而是较少使用的次要功能.添加的功能放在一个单独的类中,客户端可以对添加的功能进行选择.

优点:新添加的功能不影响被装饰类的功能,不增加被装饰类的复杂度.
缺点:需要修改客户端代码.

// component.h#ifndef COMPONENT_H#define COMPONENT_Hclass Component{public:    Component();    virtual void Operation() = 0;};#endif // COMPONENT_H

// component.cpp#include "component.h"Component::Component(){}

// concretecomponent.h#ifndef CONCRETECOMPONENT_H#define CONCRETECOMPONENT_H#include "component.h"class ConcreteComponent : public Component{public:    ConcreteComponent();    virtual void Operation();};#endif // CONCRETECOMPONENT_H

// concretecomponent.cpp#include <iostream>#include "concretecomponent.h"ConcreteComponent::ConcreteComponent(){}void ConcreteComponent::Operation(){    std::cout << "ConcreteCompoent::operation()" << std::endl;}

// decorator.h#ifndef DECORATOR_H#define DECORATOR_H#include "component.h"class Decorator : public Component{public:    Decorator(Component *tmp);    virtual void Operation();public:    Component *m_component;};#endif // DECORATOR_H

// decorator.cpp#include "decorator.h"Decorator::Decorator(Component *tmp){    m_component = tmp;}void Decorator::Operation(){    m_component->Operation();}

// concretedecorator.h#ifndef CONCRETEDECORATOR_H#define CONCRETEDECORATOR_H#include "decorator.h"class ConcreteDecorator : public Decorator{public:    ConcreteDecorator(Component *tmp);    virtual void Operation();    virtual void NewOperation();};#endif // CONCRETEDECORATOR_H

// concretedecorator.cpp#include <iostream>#include "concretedecorator.h"ConcreteDecorator::ConcreteDecorator(Component *tmp) : Decorator(tmp){}void ConcreteDecorator::Operation(){    m_component->Operation();    NewOperation();}void ConcreteDecorator::NewOperation(){     std::cout << "ConcreteDecorator::NewOperation()" << std::endl;}

客户端:

// main.cpp#include <iostream>#include "component.h"#include "decorator.h"#include "concretedecorator.h"#include "concretecomponent.h"using namespace std;int main(int argc, char *argv[]){    Component *component = new ConcreteComponent();    Component *component1 = new ConcreteDecorator(component);    component1->Operation();    return 0;}

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