[pulseaudio-discuss] [PATCH 1/4] stream-restore: add volume_is_absolute bool in client side

[Felipe Contreras]

On Mon, May 11, 2009 at 3:12 PM, Lennart
Poettering<lennart at poettering.net> wrote:
> On Mon, 11.05.09 12:56, Felipe Contreras (felipe.contreras at gmail.com) wrote:
>
>>
>> On Sat, May 9, 2009 at 3:14 PM, Lennart Poettering
>> <lennart at poettering.net> wrote:
>> > On Sat, 09.05.09 12:50, Felipe Contreras (felipe.contreras at gmail.com) wrote:
>> >
>> >> > pa_bool_t is used internally only. In the public API we only expose
>> >> > ints. pa_bool_t is defined as _Bool on C99 and int on other
>> >> > compilers. This discrepancy should not be visible to outside due to
>> >> > ABI stability issues.
>> >>
>> >> Minor comment; if you include stdbool.h you can use 'bool' which IMHO
>> >> is less ugly than _Bool. And I wonder what's the point of pa_bool_t...
>> >> if the compiler doesn't have stdbool.h, then just define 'bool' as you
>> >> would define pa_bool_t.
>> >
>> > There's not much difference between _Bool, and bool. Both are C99.
>>
>> Nope, the only difference is that 'bool' looks nicer :)
>>
>> > I guess 10 years after C99 it might be possible to drop C89
>> > support. But uh, the API uses int for all bools and we should stick to
>> > it for now.
>>
>> This is what I meant:
>>
>> #if HAVE_STDBOOL_H
>> #include <stdbool.h>
>> #else
>> typedef unsigned char bool
>> #endif
>
> Firstly that would require including config.h from public header
> files which we don't do.
>
> But more importantly this will break ABI when folks switch between C89
> and C99.
>
> Also there are lots of subtle differences between 'unsigned
> char'/'int' and 'bool'.
>
> sizof(bool) is usually sizeof(int). However sizeof(bool) is !=
> sizeof(unsigned char). In a struct defining 'bool foo:1' works fine
> and then allows assignment of 1/0. However in a struct 'int foo:1'
> allows assignment of -1/0 only.
>
> Internally we actually use a definition like you suggested, but we
> don't want to push that into the ABI and hence trigger breakage
> there. Our definition is like this:
>
> #ifdef HAVE_STD_BOOL
> typedef _Bool pa_bool_t;
> #else
> typedef int pa_bool_t;
> #endif

You said pa_bool_t is only internal, so it's safe to do:

#if HAVE_STDBOOL_H
#include <stdbool.h>
#else
typedef int bool
#endif

And s/pa_bool_t/bool/

If you have C99, pa_bool_t = _Bool, bool = _Bool
If you don't: pa_bool_t = int, bool = int

-- 
Felipe Contreras