Re: How to get id of/remove a default handler?

[David Nečas <yeti physics muni cz>]

On Fri, Jul 31, 2009 at 06:24:37AM -0700, machinegodzilla wrote:
> 
> I created an object that emits different signals depending of what has
> happened. I know the names of those signals. Now I'd like to have some of
> the signals not to be emitted from time to time. To do that I need to
> block/disconnect specific handlers. However, the methods to do that require
> handler ids to be passed as arguments.
> 
> How do I get ids of default handlers? Or maybe I need to do it some other
> way in this case?

The class closue (if you mean that by default handler, i.e. the method
passed to g_signal_newv()) is not a handler hence, it has no id and
cannot be blocked by the blocking functions.

If the class closure is of the run-last kind, you can do many things
such as using the accumulator mechanism (similarly to Gtk+ handling of
events) or stopping the signal emission in your own signal handler.

If it runs first there's not much you can do to prevent it from running.

If you do not want the signal emitted at all then simply don't emit it.
I suppose you wrote the class so you can use some flag to tell the
objects to avoid the emission and that not invoking the class closure is
safe.

If you didn't write the class then preventing the class closure from
running is not a good idea because it can bring the object into an
inconsistent state and Bad Things will happen.

For property notifications, you can also use the freeze/thaw mechanism,
providing that you are willing to let the handler run later.

Or you can make the handlers smarter so they avoid the unwelcome action
themselves. 

Hard to tell without knowing *why* you want to prevent the signals from
being emitted...

Yeti