是否有一种方法可以专门使用继承对象的一般方法

Is there a way to specialize a general method of an inherited object

本文关键字：方法 对象 继承 是否 一种      更新时间：2023-10-16

我有两个专业对象：

class Food {};
class Fruit : public Food {};
class Vegetable : public Food {};

然后我有一个父母，该类将继承：

class Parent
{
    virtual void say(Food* obj) { std::cout << "The object is food" << std::endl; }
};

和父母的继承类。

class Child : public Parent
{
    virtual void say(Fruit* obj) { std::cout << "The object is a fruit" << std::endl; }
    virtual void say(Vegetable* obj) { std::cout << "The object is a vegetable" << std::endl; }
};

我做：

std::vector<Food*> basket;
Fruit fruit = Fruit();
Vegetable vegetable = Vegetable();
basket.push_back(&fruit);
basket.push_back(&vegetable);
Child child = Child();
for (Food* food : basket)
{
    child.say(food);
}

我希望它打印"物体是水果"，然后"物体是蔬菜"，但它不起作用：我收到错误消息：从"食物*"到"水果*"的参数1的转换尚无已知转换。

是否可以在不使用typeID的情况下做到这一点，因为我听说它会导致开销。这是在线编辑器中的代码：cpp.sh/27ekc

我认为适当的解决方案是以下内容：

class Food 
{
public:
    virtual ~Food() = default;
    virtual void say() const;
};
class Fruit : public Food 
{
public:
    void say() const override { std::cout << "The object is a fruit" << std::endl; }
};
class Vegetable : public Food 
{
public:
    void say() const override { std::cout << "The object is a vegetable" << std::endl; }
};
class Parent
{
public:
    virtual ~Parent() = default;
    virtual void say(const Food& obj) const { obj.say(); }
};
class Child : public Parent {};
int main()
{
    std::vector<Food*> basket;
    Fruit fruit = Fruit();
    Vegetable vegetable = Vegetable();
    basket.push_back(&fruit);
    basket.push_back(&vegetable);
    Child child = Child();
    for (const Food* food : basket)
    {
        child.say(*food);
    }
}

编辑：根据您的评论，它基于您的健康意思。我将其解释为这些行：

class Food 
{
public:
    virtual ~Food() = default;
    virtual void say() const;
    virtual int health() const;
};
class Fruit : public Food 
{
public:
    void say() const override { std::cout << "The object is a fruit" << std::endl; }
    int health() const override { return 5; }
};
class Vegetable : public Food 
{
public:
    void say() const override { std::cout << "The object is a vegetable" << std::endl; }
    int health() const override { return 10; }
};
class Parent
{
public:
    virtual ~Parent() = default;
    virtual void say(const Food& obj) const { obj.say(); }
};
class Child : public Parent 
{
    int health;
public:
    void eat(const Food& obj) { health += obj.health(); }
};
int main()
{
    std::vector<Food*> basket;
    Fruit fruit = Fruit();
    Vegetable vegetable = Vegetable();
    basket.push_back(&fruit);
    basket.push_back(&vegetable);
    Child child = Child();
    for (const Food* food : basket)
    {
        child.say(*food);
        child.eat(*food);
    }
}

有很多不同的方法可以实现这一目标。

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