guile_gi question: gtk+ interface object?

guile_gi question: gtk+ interface object?

[Andy Tai]

question: how to create object representing Gtk+ (version 3)
interfaces? For example.

(let (model (make <GtkTreeModel>)))

would fail  because GtkTreeModel is an interface, not class derived
from GObject.

Thanks

guile_gi question: gtk+ interface object?

[Andy Tai]

question: how to create object representing Gtk+ (version 3)
interfaces? For example.

(let (model (make <GtkTreeModel>)))

would fail  because GtkTreeModel is an interface, not class derived
from GObject.

Thanks

Re: guile_gi question: gtk+ interface object?

[Maxime Devos]

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Andy Tai schreef op di 14-06-2022 om 11:52 [-0700]:
> question: how to create object representing Gtk+ (version 3)
> interfaces? For example.
> 
> (let (model (make <GtkTreeModel>)))
> 
> would fail  because GtkTreeModel is an interface, not class derived
> from GObject.

By definition, you cannot instatiate interfaces, but you can
instantiate classes derived from GtkTreeModel?  Seems like you answered
the question yourself?
Maybe guile-gi even supports defining an implementation yourself in
Scheme with GOOPS ...

Greetings,
Maxime.

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Re: guile_gi question: gtk+ interface object?

[Andy Tai]

Hi, thanks for the reply.   The interface in GObject level does not
necessarily translate as is to GOOPS at guile level...

the context of this question is

(let ((iter (make <GtkTreeIter>))
 (model (make <GtkTreeModel>)))
(define selected (tree-selection:get-selected! selection model iter))

get_selected(GtkTreeModel out model, GtkTreeeIter out iter) has two
out parameters, model and iter, but I think GOOPS does type check on
arguments before invoking a method so  both parameters must be
initialized to the expected types.
The model parameter normally is instance of a GOBject class
"implementing" the GtkTreeModel interface (at the GOBject level), and
I cannot pass in a concrete GOBject class that implements GtkTreeModel
 as GOOPS will reject such calls--GOOPS does not understand "class
implementing an interface" at the GOBject level.  So I don't know how
to initialize the model parameter.

On Tue, Jun 14, 2022 at 12:42 PM Maxime Devos <maximedevos@telenet.be> wrote:
>
> Andy Tai schreef op di 14-06-2022 om 11:52 [-0700]:
> > question: how to create object representing Gtk+ (version 3)
> > interfaces? For example.
> >
> > (let (model (make <GtkTreeModel>)))
> >
> > would fail  because GtkTreeModel is an interface, not class derived
> > from GObject.
>
> By definition, you cannot instatiate interfaces, but you can
> instantiate classes derived from GtkTreeModel?
> Maybe guile-gi even supports defining an implementation yourself in
> Scheme with GOOPS ...
>



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Andy Tai, atai@atai.org, Skype: licheng.tai, Line: andy_tai, WeChat: andytai1010
Year 2021 民國110年
自動的精神力是信仰與覺悟
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Re: guile_gi question: gtk+ interface object?

[Maxime Devos]

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Andy Tai schreef op di 14-06-2022 om 21:05 [-0700]:
> (let ((iter (make <GtkTreeIter>))
>  (model (make <GtkTreeModel>)))
> (define selected (tree-selection:get-selected! selection model iter))
> 
> get_selected(GtkTreeModel out model, GtkTreeeIter out iter) has two
> out parameters, model and iter,

Looking at 
<https://spk121.github.io/guile-gi/Function-Parameters-Arity-and-Return-Values.html>,
on the Scheme level the output parameters would be converted to return values,
so the API would be

(receive (selected iter model)
  (tree-selection:get-selected selection) ; or 
  [do things with iter and iter and model])

Doesn't seem to work though -- looking at
(generic-function-methods tree-selection:get-selected), Guile-GI incorrectly
doesn't convert it to a return value or something?

Greetings,
Maxime.

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