Re: sigc++ signals and GSignal

[Luca Cappa <luca cappa i-medlab com>]

Murray Cumming wrote:
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> > Hi folks,
> >
> > This is mainly a sigc++ question, but relates to GSignal, so I hope
> > it's on topic.
> >
> > With GSignal, you can connect a handler, or override a virtual
> > function in the object class.  In addition, you can specify whether
> > the virtual function is run first or last, and then connect signals
> > to run before /or/ after the signal if it runs last.
> >
> > With sigc::signal, I can only run signals in the order they were
> > connected.  I'd like to mimic GSignal, in that I want to provide a
> > default implementation which may be overridden, but if overridden, I
> > might not want the default to run at all.  Is this possible?
>
>
> Not easily. You could connect ane empty virtual member method as a default
> handler to your member signal. But making sure that it would be run before
> or after other handlers would be difficult. Maybe you could play with the
> signal's slot_list<> to change the calling sequence.

i guess that to add an handler after or before you could play with the 
"after" argument of that  Glib::SignalProxyNormal::connect (const 
sigc::slot_base& slot, bool after) method.

Greeetings,
Luca