On 11.08.2019, at 21:51, Marton Balint <[email protected]> wrote:
>
>
> On Sun, 11 Aug 2019, Reimar Döffinger wrote:
>
>> On 11.08.2019, at 20:41, Reimar Döffinger <[email protected]> wrote:
>>
>>> On 05.08.2019, at 23:34, Marton Balint <[email protected]> wrote:
>>>> These functions can be used to print a variable number of strings
>>>> consecutively
>>>> to the IO context. Unlike av_bprintf, no temporery buffer is necessary.
>>> Hm, is there a use-example patch I missed?
>>
>> Sorry, I see it now, and also the argument about the macro providing type
>> checking.
>> Ignore me if you feel the code is fine as-is.
>>
>>> Also is the #define ugliness worth it compared to just requiring NULL
>>> termination?
>>> You can use the sentinel function attribute to have the compiler check that
>>> users do not forget it.
>
> There is yet another approach which does not count parameters but uses a NULL
> sentinel, and is more simple:
>
> void avio_print_string_array(AVIOContext *s, const char *strings[])
> {
> for(; strings[0]; strings++)
> avio_write(s, (const unsigned char *)strings[0], strlen(strings[0]));
> }
Nitpick: I find using [0] confusing when used on a loop variable and would
consider *strings better
> #define avio_print(s, ...) \
> avio_print_string_array(s, (const char*[]){__VA_ARGS__, NULL})
>
> This might also has the benefit that __VA_ARGS__ is referenced only once,
> because for the old version some compilers (msvc) was not optimizing away the
> additional local variable and their string references which were used in the
> sizeof magic.
>
> I can change the patch to use this version if people prefer.
It also avoids potential multiple-evaluation issues, so it does seem more
robust to me.
But I admit my macro-foo is rather weak due to too much C++ use in the last
years...
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