How to define mutual friend functions?

[cyker]

I know how to define mutual friend classes. But I really wonder how to apply that to functions. Since you have to let class A see the definition(not declaration) of class B, and vise versa. And it's hard to organize the code. I just wonder: Is it possible?

[guestgulkan]

Functions can be friends of classes (is this what you want)

Functions cannot be friends of other functions.