[Help-smalltalk] questions about smalltalk and the c-call interface

[Joachim Jaeckel]

Hello,

I'm currently working on an exampel of GtkBuilder.

* Design the user-interface with glade, save it as a GtkBuilder project 
and use GTK.GtkBuilder to construct your interface on the screen. I 
think, it's nice to handle the user-interface in this way, because you 
don't have to struggle with all the ui-code in your app, except the 
callbacks and the initialization of GtkBuilder.
(Ok, don't look at my open question about GtkComboBox with the model, 
that's something you allready have to know, even if you use glade, I 
think... and btw. I still didn't find my mistake...)

And here now my questions:

- The GTK.GtkBuilder getObject: method returns currently a #{GObject}. 
That's currently the same as in C. But this returning object could be 
anthing from the GTK. GtkWindow, GtkEntry and so on. But there is no 
casting in Smalltalk, how could I create a GtkWindow from a GObject?
(Because the GObject doesn't understand e.g. 'showAll'.

Because, I don't know how to do it - if that's possible et all - I 
extended the GtkBuilder object. First with:

getObject: name as: type [
    <cCall: 'gtk_builder_get_object' returning: type
        args: #( #self #string )>
]

but that isn't working, the type parameter could not be recognized...
than I tried:

getObject: name as: type [
    (Switch value: type)
        case: 'GtkWidget'
          do: [ <cCall: 'gtk_builder_get_object' returning: #{GtkWidget}
                    args: #( #self #string )> ];
          ... so on

but that also doesn't seems to work, maybe the <cCall> pragma is not 
containable in a block. I got a "parse error, expected ']' in the line 
of the cCall.

So I currently end up with several methods like

getObjectAsWindow: name [
	<cCall: 'gtk_builder_get_object' returning: #{GtkWindow} args: 			 
#( #self #string)>
]

getObjectAsEntry ... and so on.

But I don't think, that this is the best solution. Maybe you can help me 
here with a tip how to write the cCall more generall (regarding the 
return-type) or something else. That would be nice!

Thanks in advance,
Joachim.