[gstreamer-bugs] [Bug 526814] Add disconnect notify to gst_pad_add_{data, event, buffer}_probe() functions

[GStreamer (bugzilla.gnome.org)]

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  GStreamer | gstreamer (core) | Ver: HEAD CVS




------- Comment #7 from José Alburquerque  2008-04-09 19:20 UTC -------
(In reply to comment #6)
> Last question: is the GClosureNotify significant or useful from a bindings
> point of view? I mean: do you need the closure argument passed to the notify
> callback in the bindings?
> 

For our purposes it does.  Let me explain.  In our bindings, when a probe is
added to the pad, we create extra data (a pointer to a C++ callback called a
slot) which is used to call the developer's C++ function with C++ type
arguments.  We add the probe with a pointer to the extra data and in the C
callback we cast the extra data to the C++ callback type (the slot) and then
call the user's function with the arguments "wrapped" in C++ types that the
user can use in C++ style.

The GClosureNotify is used so that when the probe is removed (the signal is
disconnected), a callback is invoked in which case we can then remove the extra
data.  Does that make sense?

> If not, it might be less confusing for other users of the API to expose a
> GDestroyNotify data_destroy instead of a GClosureNotify (passing extra
> arguments to C functions shouldn't cause any problems afaik).
> 

The problem, I think, is that a GDestroyNotify does not notify when signals are
disconnected.  Am I mistaken?  If I could find a way to be informed of when the
probe is removed, the extra data could then be removed in this way.  Do you
think this is a bit of a burden?  Thanks.


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