没有向前声明所有使用的函数的交叉依赖性？ [英] Cross dependencies without forward declaring all used functions?

问题描述

我有A类（在A.h中）取决于（B.h）中的B类，反之亦然。转发声明使用的函数工作，但这意味着我必须更新无处不在，我转发声明这些功能，在未来，ex，如果我删除或更改参数在那些函数，他们必须更新以反映更改。我不觉得这是好的做法。是否有办法解决这个问题？

I have class A (in A.h) which depends on class B in (B.h) and vice versa. Forward declaring the used functions works, but this means I have to update everywhere where I forward declared those functions in the future, ex, if I remove, or change argument in those functions they must all be updated to reflect change. I don't feel this is good practice. Is there a way around this?

谢谢

推荐答案

只需要在声明级别使用指针或引用即可，您可以这样做：

If you only need to work with pointers or references to a class at the declaration level, you can do it like this:

class B; // forward class declaration

class A {
    A(B &);
};

Bh

B.h

class A;

class B {
    B(A &);
};

B.cpp

B.cpp

#include "B.h"
#include "A.h" // now we get the full declaration of A

B::B(A &a) {
    a.foo(5);
}

这样的相互依赖性很难处理，但有时是不可避免的。

Mutual dependencies like this are tough to deal with but sometimes unavoidable.

如果 A 和 B / em>，那么您有一个系统设计问题，您需要在继续操作之前解决。

If A and B depend on the implementations of each other, then you've got a system design problem that you need to resolve before proceeding further.

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