如何在普通文件中交叉引用反向引用其他结构的结构

Question

I've two files: 1) A .h header file that cross reference a struct in a general header file that back referencing other structs inside my .h header file.

2) The struct I reference in 1) is in a general header file which does not reference other structs. 3) When I include general.h, it won't compile for other structs in 1) header file.

Here is 1) my .h file, it include general.h file in order to reference IntervalFilter:

 ...
 struct AgentConfig {
    AgentConfig();
    IntervalFilter<int> myFilter;

    other structs
...
}

But general.h file include 1) and reference other structs inside the file.

Any advice as to the syntax?

Thanks!

Answer 1

From what I understood you have two headers which include each other. You should never allow this situation, because preprocessing will yield one header above the other (given you have header guards or #pragma once), and one of those headers will always miss the stuff it needs.

There are a few ways to solve this situation:

1. Extract the independent stuff (the "other structs" you were referring to) into a third header file and resolve the 1 <-> 2 loop into a "triangle" 1 -> 3, 2 -> 3 and 1 -> 2
2. Use forward declarations instead of including the header file (won't work if you need a complete type, eg not pointer/reference)