? ? ? ? 裝飾器模式是一種結構型設計模式，它允許在運行時擴展一個對象的功能，而不需要改變其現有結構。這種模式的核心思想是通過創建一個裝飾器來動態地增強或修改原有對象的行為。裝飾器模式是繼承的一個補充，提供了比繼承更加靈活的方式來擴展對象的行為。

一、編碼

? 1、頭文件

#ifndef _DECORATE_H__
#define  _DECORATE_H__
#include <iostream>
using namespace  std;
/// 抽象被裝飾者
// template<class T,class U>  class Decoratee {
//     public:
//         virtual  U  execOpt(T t) = 0 ;
// };// template<class T,class U> class DecorateImpl: public Decoratee {
//      public:
//          U  execOpt(T t);
// };/// 抽象被裝飾者
class  Decoratee{public:int  value;virtual  void  decorateeOpt() = 0 ;
};/// 被裝飾者的具體實現
class DecorateeImpl : public Decoratee{public: DecorateeImpl();void  decorateeOpt() override;
};/// 定義裝飾器接口
class  Decorator : public Decoratee {protected:Decoratee* decoratee;public:/// @brief  裝飾器增強方法virtual  void  decoratorOpt() = 0;
};/// 擴展裝飾器A
class  DecoratorImplA : public Decorator {public:DecoratorImplA(Decoratee* decoratee);void  decorateeOpt() override;  void  decoratorOpt() override;
};/// 擴展裝飾器B
class  DecoratorImplB : public Decorator {public:DecoratorImplB(Decoratee* decoratee);void  decorateeOpt() override;  void  decoratorOpt() override;
};#endif

?2、函數定義

#include "decorate.h"// template<class T,class U>
// U  DecorateImpl<T,U>::execOpt(T t) {
//     cout << "" << endl;
// }DecorateeImpl::DecorateeImpl(){this->value = 1;
}void  DecorateeImpl::decorateeOpt(){this->value = this->value + 2; cout << "DecorateeImpl  execOpt  value = " << this->value << endl;
}DecoratorImplA::DecoratorImplA(Decoratee* decoratee) {this->decoratee = decoratee ;
}void  DecoratorImplA::decorateeOpt(){if(this->decoratee== nullptr){return;}this->decoratee->decorateeOpt();this->decoratorOpt();
}void  DecoratorImplA::decoratorOpt(){this->decoratee->value =  this->decoratee->value * 5;cout << "DecoratorImplA  execOpt  value = " <<  this->decoratee->value << endl;
}DecoratorImplB::DecoratorImplB(Decoratee* decoratee) {this->decoratee = decoratee ;
}void  DecoratorImplB::decorateeOpt(){if(this->decoratee== nullptr){return;}this->decoratee->decorateeOpt();DecoratorImplB::decoratorOpt();
}void  DecoratorImplB::decoratorOpt(){this->decoratee->value =  this->decoratee->value * 10;cout << "DecoratorImplB  execOpt  value = " <<  this->decoratee->value << endl;
}

二、測試

Decoratee*  decoratee = new DecorateeImpl();
Decorator*  decoratorA = new DecoratorImplA(decoratee);
Decorator*  decoratorB = new DecoratorImplA(decoratee);
decoratorA->decorateeOpt();
decoratorB->decorateeOpt();