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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