Re: signal emit functions
- From: murrayc t-online de (Murray Cumming)
- To: Murray Cumming <murrayc t-online de>
- Cc: Owen Taylor <otaylor redhat com>,	gtk-devel-list <gtk-devel-list gnome org>,	language-bindings gnome org
- Subject: Re: signal emit functions
- Date: 22 Sep 2001 00:52:45 +0200
On Fri, 2001-09-21 at 23:38, Murray Cumming wrote:
> On Fri, 2001-09-21 at 23:16, Owen Taylor wrote:
> > 
> > murrayc t-online de (Murray Cumming) writes:
> > 
> > > Some signals have associated emit functions. For instance,
> > > GtkAdjustment::changed has gtk_adjustment_changed(). Do these functions
> > > *ever* do anything other than just emitting the signal? Or are they just
> > > syntactic sugar?
> > > 
> > > This isn't important to most people - I'm just trying to simplify Gtk--.
> > 
> > This has been a peristant problem with Gtk-- I'm afraid.
> 
> Luckily we can now fix stuff with an API change. Sometimes you've got to
> do things wrong to find out that they're wrong.
> 
> > Only a _tiny_ subset of GTK+ signals can be emitted directly.
> > These are the signals marked with the GTK_RUN_ACTION flag.
> 
> Then I'll try to remove that functionality from the new version. I'm not
> aware of anybody using it anyway.
> 
> > And emitting these signals directly is generally not useful either
> > because they are almost always meant for use by keybindings.
> > 
> > In every other case, the signals of an object are emitted
> > only when that object intends to.
> > 
> > That is, the changed() method of GtkAdjustment:
> > 
> >  - Is documented (or should be documented) to cause ::changed
> >    to be emitted.
> > 
> >  - _Happens_ to do nothing else, currently.
> > 
> > But in no other other way is connected with the ::changed signal
> > as all. As far as the object system is concerned, it could just
> > as well cause the ::frobated signal to be emitted, or cause
> > the value of the adjustment be set to zero.
> 
> You really thing that we shouln't associate changed() with the changed
> signal in the API? changed() isn't a very descriptive function name if
> it isn't meant to suggest an association with the signal of the same
> name.
Owen explained on irc that there aren't actually many functions like
this, so it's not really an issue. 
>  
> > If a language binding maps signals directly into the objet namespace,
> > conflicts may occur that have to be resolved in some fashion,
> > but as far as GtkObject is concerned signals are in a completely
> > independent namespace from methods.
> 
> Thanks for the information.
> 
> 
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> 
> 
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