Foreign language interface (Re: input only event boxes)

[Taavi Talvik <taavi uninet ee>]

On Tue, 26 Aug 2003, Owen Taylor wrote:

..deleted..

> > I am currently trying to comprehend gobject/gtk/gnome and write foreign
> > language interface for it.
> >
> > Main problem is that *many* widgets are designed for C in mind only. And
> > there is no possibility to use just
> >
> > 	object = create.gobject("blaah")
> > 	config(object,"property","value")
> >
> > which will make foreign language interface clean and simple. Definitely
> > not optimal way (performace wise, visually), but it is always possible to
> > optimize later.
>
> If you find any widgets that can't be created with g_object_new(),
> please file a bug; the goal is that as many widgets as possible
> can be created with
>
>  g_object_new (G_TYPE_FOO, NULL);
>
> and that all widgets can be created with
>
>  g_object_new (G_TYPE_FOO, <appropriate properties>, NULL);
>
> It's certainly not intended that you can use GTK+ without using
> methods; you can't represent gtk_widget_destroy() or any other
> action as a property sanely. But creation should be possible using
> properties.

First example from top of my head is GtkTooltips:

It would be really nice, when I can do following

	Tip1 = create("GtkTooltip")
	config(Tip1, "widget", ParentWidget)
	config(Tip1, "tip-text", "Tooltip text comes here")
	config(Tip1, "tip-private", "Tooltip private text")
	...
	Container1 = create("GtkContainer")
	config(Container1, "element", Tip1)
	config(Container1, "element", Tip2)
	...
	ToolTipsCollection = create("GtkTooltips")
	config(ToolTipsCollection, "container", Container1)
	config(ToolTipsCollection, "enabled", true)
	...
	destroy(ToolTipsCollection)
	destroy(Container1)
	destroy(Tip1)

which translates quite nicely into GObject framework. GObject framework
has all required information about existence of properties, their type.
Currently GtkTooltips don't declare any properties at all:(

Many really useful actions can be represented as poperty - for example
"visible", true|"visible",false. GObject system even has mechanics
what to do, when property changes.

----
Following is probably allready offtopic (but gives some background
information):

I am trying to create "yet another Gtk binding" for Erlang programming
language. It has quite nice general gui model. For large majority
of GTK widgets I can use same model.

GUI API consists of following:

        create(ObjType, Parent, Options)
        config(Obj, Options)
        read(Obj,Option_Key)
        destroy(Obj)

and GUI interactions are send back as asynchronous messages.

Definitely not most efficient, but my aim is not to greate fast and
efficient widgets in foreing language. I  *just want to use existing
widgets*. And create/config/read/destroy interface is just enough.

Widget callbacks map quite well into asynchronous events, if I
don't do anything overly complicated (which is usually case when not
creating new widgets). Which is also usually just enough.

existing Erlang UI documentation
	http://www.erlang.org/doc/r9c/lib/gs-1.5.2/doc/html/part_frame.html

my experiments on Erlang binding
	http://home.uninet.ee/~taavi/files/erlang/xgs/

and just a code snippet using above principles

test3() ->
    Ref = start(),
    Tree= create_tree(Ref,
                      [{'GtkWindow', [{type, toplevel}, {title, "test 3"}, visible],
                        {'GtkNotebook', [visible],
                         [{'GtkFrame', [{label, "Frame 1"}, visible],
                           {'GtkHBox', [visible],
                            [{'GtkLabel', [{label, "Label One"}, visible]},
                             {'GtkTreeView',treeview, [visible],
                              []
                             }]}},
                          {'GtkFrame', [{label, "Frame 2"}, visible],
                           {'GtkVBox', box, [visible],
                            [{'GtkLabel', [{label, "Label Two"}, visible]},
                             {'GtkButton', button, [{label, "Button 1"}, visible],[]}]
                           }
                          }
                         ]
                        }
                       }
                      ]),
    signal_connect(button, 'clicked', blaah),
    signal_connect(button, 'focus', blaah),
    event_loop().

event_loop() ->
    receive ->
      {ObjId, Seq, button, 'clicked', Options} ->
          % do something when button has clicked
      {ObjId, Seq, button, 'focus', Options} ->
          % do something when object focus changes
    end,
    event_loop().

best regards,
taavi