[Gtk-sharp-list] GInterface implementation

Murray Cumming murrayc@murrayc.com
Sat, 17 Apr 2004 10:27:57 +0200

On Sat, 2004-04-17 at 00:25, Rachel Hestilow wrote:
> Essentially the problem is the same as with non-signal virtual methods 
> -- there is no easy way of implementing/overriding methods 
> automatically; instead for each method in the interface you'd need to 
> keep a delegate around for the life of the object. Additionally, 
> interfaces pose an additional problem in that there's no base class you 
> can put glue code in; you'd need a helper class of some sort that 
> managed the native<->managed conversions.

We manage this in gtkmm, but we have to use multiple virtual
inheritance, so that our Glib::Object and Glib::Interface classes share
a Glib::ObjectBase base class, and share the data in that base class.
Here's an explanatory inheritance diagram:

If you don't have multiple inheritance in C#, you might be able to use
aggregation instead.

> I get the feeling that it's mostly GtkCellRenderer that people are going 
> to want to implement.

GtkCellRenderer is not a GInterface, but you do need to register a new
GType when derving a new CellRenderer, and it has vfuncs that you need
to override.

Overriding the TreeModel Interface is fairly common though.

Murray Cumming