合成复用原则

class AbstractCar{
public:
    virtual void run() = 0;
};
class BMW:public AbstractCar{
public:
    void run()override{
        cout << "BMW run" << endl;
    }
};
class DaZhong:public AbstractCar{
public:
    void run()override{
        cout << "DaZhong run" << endl;
    }
};
#if 0
// 错误的做法
class Person : public BMW{
public:
    void drive(){
        run();
    }
};
void test1(){
    Person p;
    p.drive();
}
#endif
// 正确做法
class Person{
public:
    Person(){
        car = nullptr;
    }
    Person(AbstractCar* c){
        car = c;
    }
    void drive(){
        car->run();
        delete car;
    }
    void drive(AbstractCar* car){
        car->run();
        delete car;
    }
private:
    AbstractCar* car;
};
void test2(){
    // 方式一：
    Person* p = new Person(new BMW);
    p->drive();
    delete p;
    p = new Person(new DaZhong);
    p->drive();
    delete p;

    // 方式二：
    Person pp;
    pp.drive(new BMW);
    pp.drive(new DaZhong);
}
int main()
{
    test2();
    return 0;
}