C++多态性小心得, 指向类的指针, 继承, 虚函数

#include <iostream>
using namespace std;
class Door
{
public:
    virtual void Open() { cout<<"I'm a thinly pathetic shelter, just kick me\n"<<endl; } //运行时的多态性，如果不加virtual就是编译时的多态
//    void Open() { cout<<"I'm a thinly pathetic shelter, just kick me\n"<<endl; }//编译时的多态性
};

class SaftyDoor:public Door
{
public:
    void Open()
    {
        cout<<"Look at the key hole, do you have the key?\n"<<endl;
    }
};

class SteelDoor:public SaftyDoor
{
public:
    void Open()
    {
        cout<<"Kick? you little pathetic comic\n"<<endl;
    }
};

//还可以调用祖宗的Open()
class FakeDoor:public SaftyDoor
{
public:
    void Open()
    {
        cout<<"I am new and splendid, BUT still ";
        Door::Open();
    }
    //假冒伪劣安全门糊弄人的新功能
    void Alert()
    {
        cout<<"bee bee bee bee....\n"<<endl;
    }
};

void main()
{
    while(1)
    {
        Door* door_BoughtWhenIAmPoor = new Door();
        Door* door_BoughtWhenIEarnedMoney = new SaftyDoor();
        Door* door_BoughtWhenIAmRich = new SteelDoor();
        Door* door_BoughtWhenIWatchedDoorAds = new FakeDoor();

        door_BoughtWhenIAmPoor->Open();
        door_BoughtWhenIEarnedMoney->Open();
        door_BoughtWhenIAmRich->Open();
        door_BoughtWhenIWatchedDoorAds->Open();

        delete door_BoughtWhenIAmPoor;
        delete door_BoughtWhenIEarnedMoney;
        delete door_BoughtWhenIAmRich;
        delete door_BoughtWhenIWatchedDoorAds;

        cin.get();
    }
}

运行结果




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最近在工作中用了几套三方SDK写程序, 发现一个特点, 这几套SDK在使用上都一个风格, 形如本例

本例是由百度百科里的例子改来的, 原例都是A,B,C莫名其妙的变量名, 函数名, 难看!

改成这样就好多了, 有助理解.

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结论:
1.    这种风格似乎使程序更好扩展, 子类可以重写属于自己的方法, 也可以调用父类或祖宗类的方法, 而却用祖宗类的类型定义
2.    由于用的是指针, 所以可以实现动态分配类占的空间, 随时释放