[computer-go] C++: #include vs .h files

[Dave Denholm]

Peter Drake <drake at lclark.edu> writes:

> That mostly worked, but I have a more subtle problem.
>
> I have two classes, BitBoard and BoardState. Each needs to know about
> the other because the other appears in field declarations or method
> signatures. If I put
>
> #include "BoardState.h"
>
> in BitBoard.h and vice versa, there is obviously a circularity. How
> to get around this?
>

The earlier suggestion of surrounding the body of a header file with
an ifdef would fix this.

BitBoard.h has

#ifndef BITBOARD_H
#define BITBOARD_H
#include <BoardState.h>
...
#endif

and similarly for BoardState.h

Then whichever you include first will include the other, but it will
not continue to recurse because when the second re-includes the first,
it will find nothing to do because its guard is already defined.

dd
-- 
Dave Denholm              <ddenholm at esmertec.com>       http://www.esmertec.com