[gstreamer-bugs] [Bug 510301] New: GstStructure immutability problem when creating new C++ bindings

[GStreamer (bugzilla.gnome.org)]

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  GStreamer | gstreamer (core) | Ver: 0.10.15
           Summary: GstStructure immutability problem when creating new C++
                    bindings
           Product: GStreamer
           Version: 0.10.15
          Platform: Other
        OS/Version: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: Normal
         Component: gstreamer (core)
        AssignedTo: gstreamer-bugs at lists.sourceforge.net
        ReportedBy: jaalburquerque at cox.net
         QAContact: gstreamer-bugs at lists.sourceforge.net
     GNOME version: 2.19/2.20
   GNOME milestone: Unspecified


In trying to create new C++ bindings for gstreamer
(http://svn.gnome.org/svn/gnomemm/gstreamermm/trunk), I get the following two
warnings when creating a GstQuery:

(lt-oggplayer:7134): GStreamer-CRITICAL **: gst_structure_id_set_valist: 
assertion `IS_MUTABLE (structure)' failed

(lt-oggplayer:7134): GStreamer-CRITICAL **: gst_structure_id_set_valist: 
assertion `IS_MUTABLE (structure)' failed

We've bound quite a bit of gstreamer API and just completed GstQuery.  The
reason these warnings occur is that in the bindings we've created derived
classes for all the GstQuerys in the API and to parse the query (which is
always returned by the "creation" methods as a "smart pointer" to the base
class though the class is actually a derived one), the smart pointer needs to
be be cast as a pointer to a derived class.

The problem is that the GstQuery is referenced once on creation and a cast of
the smart pointer creates another smart pointer, referencing the GstQuery
again.  When the query is sent to the GstElement, the warnings appear.  I can
provide code snippets of how the warnings are generated if necessary and
explain where in our bindings they occurs.


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