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Subject: 1 standard generic callback system

1 standard generic callback system

From: Jonathan Gordon <>
Date: Wed, 6 Jun 2007 00:32:50 +1000

hey all,
so, in IRC we somehow got onto the problem that the filebrowser needs
to know when a track changes (so the follow playlist can work
properly), and scrobbler and database also need to know when this
playback.c has a few callbacks but only allows one function to be
registered for each, which causes a bit of a mess in playback.c (and
is one reason why scrobbler is broken on hwcodec.)

My attached patch addresses this issue, by taking the existing
ata_notify_callback code and extending it so functions are registered
as callback for certain events.
so, what would happen is database, scrobbler and tree would all
register individual callbacks on the PLAYBACK_TRACK_CHANGED event,
then playback.c (or mpeg.c) would call call_event_callbacks() with the
PLAYBACK_TRACK_CHANGED event id and some known data which would then
call each registered function (for that id).

Firstly, my reasoning for having a seperate module for this is so
playback.c doesnt have the extra clutter which just makes it more
difficult to work in then it already is, It makes adding more
callbacks for an event very simple, and hopefully makes the code a bit
smaller if this is current used in a similar way in other parts of the

The reason for the event id and a single array for the callbacks is
that it wastes less ram than having a seperate array for each event

At the moment, all this patch does it replace the existing ata
callback stuff with this, it doesnt touch playback yet. I just wanted
to get this out and hopefully get some feedback on weather this is
good or not?

Also, which other events would be usefull to add?

Questions, comments?


Received on 2007-06-05

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