[Freeciv-Dev] Re: PATCH change_specialist

[Stewart Adcock <stewart@xxxxxxxxxxxxxxxxxxxxxx>]

Hi,

Gregor Zeitlinger wrote:

> On Mon, 17 Dec 2001, Stewart Adcock wrote:
>
> > Maybe:
> > #if _USE_C99_SOURCE
> > typedef _Bool boolean;
> > #else
> > typedef short boolean;
> > #endif
> great. That's what I was looking for. But int should be more suitable as
> it's faster, AFAIK
I doubt that it's faster with any sensible compiler.  Of course you can allow the 
compiler to make the choice about integer type using "typedef enum {false, true} 
boolean;".  gcc typically chooses unsigned short for that, I believe.


Adam Olsen wrote:

> On Mon, Dec 17, 2001 at 01:24:17PM -0800, Stewart Adcock wrote:
>
>>Why not use the C99 boolean type when available (i.e. in gcc), which can
>>be checked in the configure script, and default to int, or short, or
>>something otherwise?
>>
>>Maybe:
>>#if _USE_C99_SOURCE
>>typedef _Bool boolean;
>>#else
>>typedef short boolean;
>>#endif
>>
>>Then the compiler will check it, when the feature is available.
>>
>
> I think it's better to use typedef enum {false, true} boolean; since
> then gdb can handle it.
What exactly can't gdb handle about _Bool?  Everyone know that false is 
0 and true is 1, right? ;)
Of course, the best approach, IMHO, would be to use sdtbool.h, and 
create our own stuff if that isn't available.  Something like this would 
probably do the trick:
#ifdef HAVE_STDBOOL_H
# include <stdbool.h>
#else

/* Some platforms already define true and false.  To the
 * best of my knowledge, it is always safe to zap these.
 */
# ifdef false
#  undef false
#  undef true
# endif

# ifndef __cplusplus
/* By defining _Bool as an enum type we get to see symbolic
 * names in gdb.
 */
typedef enum { false, true } _Bool;
# else
typedef bool _Bool;
# endif
# define bool _Bool

/* According to ISO C99, the boolean stuff must be available
 * in preprocessor directives and __bool_true_false_are_defined
 * should be true.
 */
# define false 0
# define true 1
# define __bool_true_false_are_defined 1

#endif

Obviously, the check for stdbool.h needs to be added to the configure 
script.
Stewart.


--
____________________________________________________________________
Stewart Adcock   stewart@xxxxxxxxxxxxxxxx   www.stewart-adcock.co.uk
Dept. Chemistry & Biochemistry, University of California, San Diego
4234 Urey Hall, 9500 Gilman Drive, La Jolla, CA 92093-0365 USA
lab: +1 858 534 0956 home: +1 858 453 2577