抽象类中的虚拟类 [英] virtual class in abstract class

问题描述

你好:)我想问一下，是否可以做这样的事情:

Hello :) i would like to ask, if it's posible to make something like this:

我有基类(父类)A和其他三个类(子类)B C D在A类中，我有虚函数，没关系.但是如果我需要一个虚拟课怎么办?

i have base class (parent) A and three other classes (childs) B C D in class A, i have virtual functions, that's ok. but what if i need a virtual class ?

class A 
{
public:
    virtual int func1()=0;
    virtual int func2()=0;

    virtual class AB; // !!!!???
};

class B
{
public:
    int func1();
    int func2();

    class AB
    {
    public:
    ....
    };
};

类B C D与类B相同.现在，我想创建类实例，它应该自动将类重定向"到B或C D等功能的实例.

classes B C D are same as class B. Now, i would like to create class instance and it should automaticly "redirect" class to instance of B or C D etc like functions.

有可能吗?我希望您能理解:)非常感谢您的回答.

is it possible ? i hope, you understand :) Thank you very much for answer.

推荐答案

这从根本上是不可能的.在运行时确定虚拟函数调用.一个类在编译时更改程序的行为.除非运行时和编译时间是同一时间(即使用JIT或其他动态代码生成器)，否则您无法在运行时确定编译时.在标准C ++中，这是不可能的.

This is fundamentally impossible. A virtual function call is determined at runtime. A class changes the behaviour of the program at compile-time. You can't make a compile-time determination at runtime unless runtime and compiletime are the same time, i.e. using a JIT or other dynamic code generators. In standard C++, this is impossible.

您可以做的是拥有一个基类AB，该基类具有一个虚函数，该虚函数创建一个可以从该基类继承的类，然后返回一个指向该基类的指针.

What you CAN do is have a base class AB, with a virtual function that creates a class that is guaranteed to inherit from this base class, and then return a pointer to that.

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