Reversing the #include idiom

There's an idiom in C and C++ whereby of you include a header file, you write

#ifndef FILE_H_INCLUDED
#define FILE_H_INCLUDED

// stuff

#endif

It occurs to me that it should actually be

#ifndef EXCLUDE_FILE1_H
#define EXCLUDE_FILE1_H

#endif

This is a minor point, however it means that you can legitimately exclude certain header files if for some reason you don't want to include them:

gcc foo.c -DEXCLUDE_FILE1_H