Re: newbie question about g_object unref()

[David NeÄas <yeti physics muni cz>]

On Fri, Nov 19, 2010 at 01:21:44PM +0000, N James Bridge wrote:
> Thanks for all your contributions. I have now found G_IS_OBJECT(), which
> is obviously the way to test whether the memory has been released or
> not.

It obviously ISN'T.

If the memory was released then the argument is no longer a valid
GTypeInstance pointer as required (see the documentation).

If you want to nullify a pointer when you release your reference (which
I also find often useful as once you released your reference you may not
be longer sure the object exists at all) you should use a macro for
that, I use one defined approximately

    do { if (obj) { g_object_unref(obj); (obj) = NULL; } } while (0)

which, beside nullifying the pointer, is idempotent and can also be
freely used on NULL pointer.

Yeti