Newsgroups: comp.lang.c++
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From: haydens@natasha.juliet.ll.mit.edu (Hayden Schultz)
Subject: Boolean confusion
Message-ID: <HAYDENS.91May23103233@natasha.juliet.ll.mit.edu>
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Organization: M.I.T. Lincoln Lab - Group 42
Distribution: comp.lang.c++
Date: 23 May 91 10:32:33


I've been browsing through include files and it seems that everyone in
the world who ever created a C++ include file created some definition to
support boolean variables. I've seen BOOL bool Bool BOOLEAN boolean
Boolean bool_t BOOL_T, ... Some are #defines, some are typedefs.
Some folks like to associate them with char, unsigned char, int, long,
or enum. Some packages (like XView) must have used a random number
generator to decide which definition would be used for each separate
include file-- I doubt that anyone could be that inconsistant unless
it was deliberate.

So my question is, how can I choose one definition (my own, or someone
else's) for boolean variables, and still remain insulated from the sea
of boolean definitions in assorted include files? For that matter, am
I insulated even without a boolean definition of my own?

I suppose I could pick some extreamly unlikely name for my boolean
variable type, but I really don't want to. One reason is that it makes
code so much clearer to have clear straighforward class and type
names.

The best I can think of right now is to always include "foreign"
include files first, then my own. In my own include files I can do
something like:

#ifdef Bool
#undef Bool
#endif
typedef enum {FALSE, TRUE}	Bool;

I suppose that I could still take a hit from a macro, or inline
function. I don't think I'm immune from name space conflicts either.
The biggest thing I'd like to avoid is having the same class have
different sizes in different include files due to include file
interference.

What's the best way to do this?

	Thanks,

	Hayden Schultz (haydens@juliet.ll.mit.edu)
	MIT Lincoln Lab
	(617) 981-3685