Re: Unboxing GValues into WCPs

[Andy Wingo]

On Sat, 31 Jul 2004, Andreas Rottmann wrote:

> Hi!
> 
> I'm messing a bit with the GStreamer bindings, and am trying to write
> a metadata extractor. I have a subtle problem with a signal callback:
> the arguments for the attached procedure are passed as GValues, and
> one of the arguments is an GstTagList*. From what I can see, there is
> currently no way to get the corresponding <gst-tag-list*> WCP out of
> the GValue. Thus we need something like gvalue->wcp, which is an
> inherently unsave procedure, since you need to know the WCT that is
> contained in the GValue.

I don't like inherently unsafe procedures in scheme. It should not be
possible to crash guile from scheme.

In this case, it would be better to implement a registry of
GType->wrap-value procedures somewhere in guile-gobject and have this
work automatically. Opaque types are not useful.

Any problem with that?

BTW: I haven't gotten around to visiting your guile-gstreamer patch. But
I will say that 0.8.4 should contain the gst_tag_to_pointer procedure,
so the patch to the defs file is unnecessary.

Regards,
--
Andy Wingo <address@hidden>
http://ambient.2y.net/wingo/