Re: MVC and GTK

[Darin Fisher <dfisher jagger me berkeley edu>]

Timothy M. Shead wrote:

> Paul Barton-Davis wrote:
>
> > I'd like to once again mention that it would be nice to see a roadmap
> > entry for GTK that includes making the toolkit much more
> > Model-View-Controller friendly. I would be quite willing to help with
> > the design and/or part of the implementation of this.
> >
> > I've just spent several hours having to hack together solutions for a
> > system in which there are 3 different windows all displaying
> > "Controllers" for the same "Model", and its really ugly doing this in
> > GTK.
> > The typical solution that I have to adopt is to use a flag that tells
> > the handler for (e.g) "toggled" to do nothing, so that I can safely 
> > call button.set_active (TRUE) without creating an infinite
> > loop. This is not very friendly, and given the apparently widespread
> > acceptance that MVC is the "correct" way to write GUI's of moderate or
> > greater complexity, it would be very nice to see GTK+ support this
> > internally.
> > At the very least, we need ways to inhibit the emission of signals
> > from widgets so that they can be adjusted "silently" when notification
> > is received that things have changed (e.g. as a result of action in
> > another view) and they need to be updated to reflect that.
>
>
> The "toggled" signal is frustrating.  The call to gtk_signal_connect 
> returns a "handler ID" that you can use in subsequent calls to 
> gtk_signal_handler_block() and gtk_signal_handler_unblock() to 
> temporarily disable a specific signal.
>
> In practice, keeping track of individual handler IDs is tedious, so 
> the SDPGTK library provides BlockAllEvents() and UnblockAllEvents() 
> methods at its container level, which works out well.
>
> Regards,
> Timothy M. Shead
> tshead k-3d com
>
>
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The gtk_signal_handler_{un}block_by_{func,data} are also quite handy as 
they allow you to forgo storing the handler ID.  If you are writing C++ 
code on top of GTK, {un}blocking a signal can be as easy as:

gtk_signal_handler_{un}block_by_data(GTK_OBJECT(mWidget), this);

provided, of course, that you passed "this" to gtk_signal_connect.

Darin