Re: [gtk-list] Gtk--: RFyC: gtk-- experiences (1 year of usage)

[Tero Pulkkinen <terop assari cc tut fi>]

Christof Petig <christof.petig@wtal.de> writes:
> *Some assorted Gtk-- experiences*
> 
>    o Never try to copy a Widget. This might change in future revisions of
>      gtk-- (>0.10). But up to now it is lethal. So avoid:
>    o     widget=other_widget; and     vector<Gtk_Widget>.push_back(widget);.
>      [[Havoc]] explains in detail what is going wrong. Instead use
>      vector<Gtk_Widget*>.push_back(new Gtk_Widget());.
> 
>      I have been told ([[Tero, Sep 98]]) that vector<auto_ptr<Gtk_Widget>>
>      should provide even more enhanced functionality but I haven't found any
>      docu about these new gtk-- features, yet!   

hmm, I'm not really sure if auto_ptr<> is any better for exactly this
situation. Safest bet right now is use vector<Gtk_Widget*> myvec; and have
destructor delete the objects. (seems that it'd really need to be
refcouted pointer object, if you want to store it in vector<> -- auto_ptr
can invalidate the pointer silently => not good for a vector<>. :)

However, Gtk_Container provides way to do this:
   auto_ptr<Gtk_Widget> buttonwidget(new Gtk_Button);
   add(buttonwidget);

or use pack_start/pack_end or other insertion methods of different
Gtk_Container's. This "Gtk_ObjectHandle<>" interface for these methods
were added to avoid forcing people to store objects they only
construct and then forget... => now the only code that needs to know
about the objects are constructor adding the widget to container. The
Gtk_Container will handle deletion of objects inserted to the
container that way. There is no documentation of this feature - and
you should use it carefully and report all bugs... .)  (== it has not
been used much.)

>    o Deleting a widget tree has issues. So far calling hide() and then
>      deleting the widget should be safe for windows/dialogs. But this is only
>      safe for widgets which are not contained within another widget (e.g. a
>      Box). Gtk-- has no gtk_container_remove equivalent, yet.

yup. The thing we should do is to add support for STL's container requirements
for these cases... (erase method...)

>    o You might work around deleting widgets by hiding them and reusing them
>      (ugh!)

yuck:)

>    o You cannot delete a Widget while processing a callback from it. For me
>      the following works:

wasnt there added that delete_self() method? maybe it works?


(anyway, I'll look into the other issues from the mail later.. :)
-- 
-- Tero Pulkkinen -- terop@modeemi.cs.tut.fi --