Re: [FFmpeg-devel] [PATCH v4 3/5] avutil: add obj-c helpers into header-only include

[Aman Karmani <ffmpeg@tmm1.net>]

On Sun, Dec 19, 2021 at 9:09 AM James Almer <jamrial@gmail.com> wrote:

> On 12/17/2021 5:04 PM, Aman Karmani wrote:
> > From: Aman Karmani <aman@tmm1.net>
> >
> > Reviewed-by: Ridley Combs <rcombs@rcombs.me>
> > Signed-off-by: Aman Karmani <aman@tmm1.net>
> > ---
> >   libavutil/objc.h | 32 ++++++++++++++++++++++++++++++++
> >   1 file changed, 32 insertions(+)
> >   create mode 100644 libavutil/objc.h
> >
> > diff --git a/libavutil/objc.h b/libavutil/objc.h
> > new file mode 100644
> > index 0000000000..0db993f716
> > --- /dev/null
> > +++ b/libavutil/objc.h
> > @@ -0,0 +1,32 @@
> > +/*
> > + * This file is part of FFmpeg.
> > + *
> > + * FFmpeg is free software; you can redistribute it and/or
> > + * modify it under the terms of the GNU Lesser General Public
> > + * License as published by the Free Software Foundation; either
> > + * version 2.1 of the License, or (at your option) any later version.
> > + *
> > + * FFmpeg is distributed in the hope that it will be useful,
> > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> > + * Lesser General Public License for more details.
> > + *
> > + * You should have received a copy of the GNU Lesser General Public
> > + * License along with FFmpeg; if not, write to the Free Software
> > + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
> 02110-1301 USA
> > + */
> > +
> > +#ifndef AVUTIL_OBJC_H
> > +#define AVUTIL_OBJC_H
> > +
> > +#include <Foundation/Foundation.h>
> > +
> > +static inline void ff_objc_release(NSObject **obj)
> > +{
> > +    if (*obj) {
> > +        [*obj release];
> > +        *obj = nil;
> > +    }
> > +}
> > +
> > +#endif /* AVUTIL_OBJC_H */
>
> This breaks checkheaders. It should be added to SKIPHEADERS with the
> corresponding check.
>

Sorry, will fix.


>
> Also, why is this in lavu if it's ultimately only used in lavfi? And
> does it need to be a separate header at all? It's apparently not even C.
>

It is a generic helper requested by rcombs. I think the plan is to reuse it
in other filters/decoders/encoders written in obj-c.

One of the reasons is becausing calling `[nil release]` can crash.

You're right that it is not C, its obj-c and that's why it was simpler to
have it be an include only header. I'm not sure if using a different
extension would have been preferred.

Aman


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