一. 類圖
InterfaceA:虛基類,聲明了許多“被裝飾者”通用的接口函數
InterfaceB:虛基類,繼承自InterfaceA, 聲明了許多“裝飾者”通用的接口函數
A:被裝飾者,實作了InterfaceA中的接口函數
B、C、D:裝飾者,每個裝飾者都含所有一個InterfaceA的指針,用來指向具體的裝飾者。
二. 代碼實作
class InterfaceA
{
public:
InterfaceA() {}
virtual ~InterfaceA() {}
virtual string getDescription() = 0;
};
class InterfaceB : public InterfaceA
{
public:
InterfaceB() : InterfaceA() {}
virtual ~InterfaceB() {}
};
class A : public InterfaceA
{
public:
A() {}
~A() {}
string getDescription()
{
return string("I am A");
}
};
class B : public InterfaceB
{
public:
B(InterfaceA* p): m_p(p){}
~B() {}
string getDescription()
{
return m_p->getDescription() + ",decorated by B";
}
private:
InterfaceA* m_p;
};
class C : public InterfaceB
{
public:
C(InterfaceA* p) : m_p(p) {}
~C() {}
string getDescription()
{
return m_p->getDescription() + ",decorated by C";
}
private:
InterfaceA* m_p;
};
int main(int argc, char* argv[])
{
A* pA = new A;
cout<< pA->getDescription(); //直接調用A::getDescription
cout << endl;
//用B來裝飾A,形成BA
B* pBA = new B(pA);
cout << pBA->getDescription();
cout << endl;
//用C來裝飾BA,形成CBA
C* pCBA = new C(pBA);
cout << pCBA->getDescription();
cout << endl;
getchar();
return 0;
}
運作結果如下圖: