Re: maemomm: virtual function overrides

[VLG <3rdshift comcast net>]

This has been covered in 'Changes to gtkmm' chapter [1] of "Programming
with maemomm." Another major this you are going to face is disabled
exception handling. You can handle this same way by writing wrappers:

std::string
MyKlass::locale_from_utf8 (const Glib::ustring& utf8_string_)
{
	std::string result;

#ifdef GLIBMM_EXCEPTIONS_ENABLED
	try {
		result = Glib::locale_from_utf8 (utf8_string_);
	}
	catch (Glib::ConvertError& e) {
		/* cannot convert */
	}
#else
	std::auto_ptr<Glib::Error> err;
	result = Glib::locale_from_utf8 (utf8_string_, err);
	/* check the err */
#endif
	return result;
}


[1] <http://maemomm.garage.maemo.org/docs/tutorial/html/ch04s02.html>

--Vlad

On Sun, 2007-11-11 at 12:19 +0100, Armin Burgmeier wrote:
> On Sun, 2007-11-11 at 07:50 +0000, John Steele Scott wrote:
> > I have a Gtkmm application which uses a custom widget derived from 
> > Gtk::DrawingArea. This widget overrides the virtual functions of the 
> > parent, such as e.g.:
> > 
> > void PlotCanvas::on_realize()
> > {
> >   Gtk::DrawingArea::on_realize();
> > 
> >   // do some other stuff . . .
> > }
> > 
> > This works fine on my Ubuntu Gutsy machine, but when I try to compile 
> > this in the Maemo sandbox, it fails because there is no 
> > Gtk::DrawingArea::on_realize(). Similarly, other such signal handlers are 
> > never called, it seems that they need to be explicitly connected via 
> > their signal proxies.
> > 
> > Since I'm new to Gtkmm, I'd like to know: is this difference due to the 
> > version of Gtkmm in Ubuntu Gutsy being much newer than the version in 
> > Maemo Bora, or is it a core difference between the Hildon and vanilla 
> > versions of Gtkmm? (I imagine it might be the latter, to save code size.)
> 
> It's exactly that. Default signal handlers are, among other API,
> disabled in maemo to save code size. It shouldn't be much of a deal,
> though, since you just can do something like
> 
> #ifndef GLIBMM_DEFAULT_SIGNAL_HANDLERS_ENABLED
> signal_realize().connect(sigc::mem_fun(*this, &PlotCanvas::on_realize));
> #endif
> 
> in your constructor. It gets trickier if you want to override GObject
> vfuncs (those that end in _vfunc() in gtkmm).
> 
> Armin
> 
> > If the difference is due to the version number of Gtkmm, in which version 
> > did this feature (virtual functions for signals) get included in Gtkmm? 
> > Does the Maemo Chinook version of Gtkmm have overridable virtual 
> > functions?
> > 
> > cheers,
> > 
> > John
> > 
> > _______________________________________________
> > gtkmm-list mailing list
> > gtkmm-list gnome org
> > http://mail.gnome.org/mailman/listinfo/gtkmm-list
> 
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