装饰模式（Decorate Pattern）

装饰模式（Decorate Pattern）

• 描述：动态地将责任附加到对象上。若要扩展功能，装饰者提供了比继承更有弹性的代替方案
• 注意：装饰者和被装饰者必须是一样的类型
• 缺点：利用装饰着模式，常常造成设计中有大量的小类，可能会造成使用此API程序员的困扰
  
• 代码举例：

class Beverage
{
public:
    virtual std::string getDescription();
    virtual float cost();
}

class DarkRoast : public Beverage
{
public:
    virtual std::string getDescription()
    { return "DarkRoast";}
    
    virtual float cost()
    { return 1.0; }
}

class CondimentDecorator : public Beverage
{
public:
    CondimentDecorator(Beverage* pBeverage);
    virtual std::string getDescription();
    virtual float cost();
    
    Beverage* m_pBeverage;
}

class Milk : public CondimentDecorator
{
public:
    Milk(Beverage* pBeverage):CondimentDecorator(pBeverage)
    { }
    
    std::string getDescription()
    { return m_pBeverage->getDescription() + "Milk"; }
    
    float cost()
    { return m_pBeverage->cost() + 0.5; }
}

int main()
{
    Beverage* beverage = new DarkRoast();
    beverage = new Milk(beverage);
    beverage->getDescription();//"DarkRost + Milk"
    beverage->cost();//1.5
}

来源：CSDN

作者：冻融

链接：https://blog.csdn.net/wwhx27/article/details/104113532