装饰者模式

   装饰者模式：动态地将责任附加到对象上。想要扩展功能，装饰者提供有别于继承的另一种选择。——《HEAD FIRST 设计模式》

   我的c++代码：

#ifndef DESIGN_DECORATOR_H_
#define DESIGN_DECORATOR_H_

#include <string>

class Beverage
{
public:
    virtual ~Beverage(){}
public:
   virtual std::string getDescription();
   virtual int cost();
protected:
   std::string m_descri;
};

class CondimentDecorator:public Beverage
{
public:
    virtual ~CondimentDecorator(){}
};

////////////////////////////////
class HouseBlend:public Beverage
{
public:
    HouseBlend();
    virtual ~HouseBlend(){}
public:
    virtual std::string getDescription();
    virtual int cost();
};

class DarkRoast:public Beverage
{
public:
    DarkRoast();
    virtual  ~DarkRoast(){}
public:
    virtual std::string getDescription();
    virtual int cost();
};

class Espresso:public Beverage
{
public:
    Espresso();
    virtual ~Espresso(){}
public:
    virtual std::string getDescription();
    virtual int cost();
};

class Decaf:public Beverage
{
public:
    Decaf();
    virtual ~Decaf(){}
public:
    virtual std::string getDescription();
    virtual int cost();
};
////////////////////////////////
class Milk:public CondimentDecorator
{
public:
    Milk(Beverage* b);
    virtual ~Milk(){}
public:
    virtual std::string getDescription();
    virtual int cost();
private:
    Beverage* m_b;
};

class Mocha:public CondimentDecorator
{
public:
    Mocha(Beverage* b);
    virtual ~Mocha(){}
public:
    virtual std::string getDescription();
    virtual int cost();
private:
    Beverage* m_b;
};

class Soy:public CondimentDecorator
{
 public:
    Soy(Beverage* b);
    virtual ~Soy(){}
 public:
    virtual std::string getDescription();
    virtual int cost();
 private:
    Beverage* m_b;
};

class Whip:public CondimentDecorator
{
public:
    Whip(Beverage* b);
    virtual ~Whip(){}
public:
    virtual std::string getDescription();
    virtual int cost();
private:
    Beverage* m_b;
};
#endif // DESIGN_DECORATOR_H_

#include "decorator.h"

std::string Beverage::getDescription()
{
    return this->m_descri;
}

int Beverage::cost()
{
    return 0;
}

HouseBlend::HouseBlend()
{
    this->m_descri = "HouseBlend";
}

std::string HouseBlend::getDescription()
{
    return Beverage::getDescription();
}

int HouseBlend::cost()
{
    return 1;
}

DarkRoast::DarkRoast()
{
    this->m_descri = "DarkRoast";
}

std::string DarkRoast::getDescription()
{
    return Beverage::getDescription();
}

int DarkRoast::cost()
{
    return 2;
}

Espresso::Espresso()
{
    this->m_descri = "Espresso";
}

std::string Espresso::getDescription()
{
    return Beverage::getDescription();
}

int Espresso::cost()
{
    return 3;
}

Decaf::Decaf()
{
    this->m_descri = "Decaf";
}

std::string Decaf::getDescription()
{
    return Beverage::getDescription();
}

int Decaf::cost()
{
    return 4;
}

Milk::Milk(Beverage* b)
{
    this->m_b = b;
}

std::string Milk::getDescription()
{
    return this->m_b->getDescription() + ",Milk";
}

int Milk::cost()
{
    return this->m_b->cost() + 1;
}

Mocha::Mocha(Beverage* b)
{
    this->m_b = b;
}

std::string Mocha::getDescription()
{
    return this->m_b->getDescription() + ",Mocha";
}

int Mocha::cost()
{
    return this->m_b->cost() + 2;
}

Soy::Soy(Beverage* b)
{
    this->m_b = b;
}

std::string Soy::getDescription()
{
    return this->m_b->getDescription() + ",Soy";
}

int Soy::cost()
{
    return this->m_b->cost() + 3;
}

Whip::Whip(Beverage* b)
{
    this->m_b = b;
}

std::string Whip::getDescription()
{
    return this->m_b->getDescription() + ",Whip";
}

int Whip::cost()
{
    return this->m_b->cost() + 4;
}

          个人感悟：待留。