[FFmpeg-devel] [PATCH v2 1/3] avutil/dict: add av_dict_pop

[Anton Khirnov]

Quoting Andreas Rheinhardt (2023-10-20 16:00:45)
> Anton Khirnov:
> > Quoting Andreas Rheinhardt (2023-07-03 20:02:25)
> >> Marvin Scholz:
> >>> I honestly can't think of a sensible API design for this,
> >>> if you have any idea feel free to share.
> >>>
> >>
> >> The only way I can think of that allows this is for the user to pass a
> >> pointer to a (const) AVDictionaryEntry, namely the entry that the user
> >> wishes to pop. This is of course cumbersome, because it would be two
> >> function calls.
> > 
> > We could start guaranteeing that entries with the same key are always
> > returned in insertion order. Now that I think of it there's some code in
> > ffmpeg CLI that relies on that.
> > 
> 
> IIRC this is not true correctly, because removing an entry changes the
> order of the remaining entries (we don't memmove the remaining entries
> into the new position; instead we move the last entry to the now vacant
> slot).

I am aware - that code is strictly speaking incorrect. It happens to
work because nothing ever gets removed from the option dicts. We could
consider changing the internal representation somehow, so that all
values for a key are grouped together.

-- 
Anton Khirnov