On Sat, Feb 19, 2005 at 11:47:15PM +0000, Roger Leigh wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Ben Johnson <ben@xxxxxxxxx> writes: > > > I made a class that defines several _new() functions, which take various > > parameters. I now want to subclass from this and keep my various _new() > > functions with more or less the same parameters, and I want the behavior > > to stay the same too. I don't see anything in the documentation about > > how to do it though. anyone know? > > What about a factory function which allows one to choose the specific > derived type. For example, > > GtkGroupedToggle * > gtk_grouped_toggle_new_from_widget (GType group_toggle_type, > GtkGroupedToggle *group) > GtkGroupedToggle *new_toggle = NULL; > > g_return_val_if_fail(g_type_is_a(group_toggle_type, > GTK_TYPE_GROUPED_TOGGLE) == TRUE), NULL); > > new_toggle = g_object_new (type, NULL); > if( new_toggle ) > new_toggle = gtk_grouped_toggle_add_to_list (new_toggle, group); > > return GTK_WIDGET(new_toggle); > } > > You now don't need any _new() functions for derived types. That's an interesting idea. So my objects of derived types would be created... like this?: w = gtk_grouped_toggle_new_from_widget (HPNT_TYPE_GROUPED_TOGGLE, NULL); huh. that's pretty cool. The base type doesn't need to know anything about derived types, but it supports them anyway and cuts down on coding. I might do that. (do I have it right? ...) #define HPNT_TYPE_GROUPED_TOGGLE (hpnt_grouped_toggle_get_type ()) > Also, isn't it bad practice to have arguments to a _new() function > which are not construction parameters? Wouldn't it be better to add > to group manually, or have g_object_new in a method of the container > so it can't exist independently? I'm not sure what you mean by construction parameters. I figure anything that aids in construction can be a construction parameter if you want it to be. I have these _from_from_widget() constructors because it simplifies the creation. My constructors for this are patterned after the GtkRadioButton class which the new one is very similar to. GtkRadioButton has a number of _new_from_widget*() funcs. Thanks! - Ben _______________________________________________ gtk-list@xxxxxxxxx http://mail.gnome.org/mailman/listinfo/gtk-list
