Re: [gtkmm] Problem in CustomCellrenderer

["Andrew E. Makeev" <andrew solvo ru>]

Murray Cumming wrote:

> > Good day,
> >
> > Actually, it is derivation problem for custom combobox that used for
> > editing cell value.
> >
> > I used cellrenderercustom example to implement my program where user
> > should edit value in TreeView as combobox, entry or spinbutton. Also I
> > created interface class that allow me similar access to all those 3
> > fields using one CustomCellrenderer class. See derivation for my combobox:
> >
> > class PopupEntry : public Gtk::EventBox, public Gtk::CellEditable
> >    
>
> This is multiple inheritance of base classes that share a common base
> class. So you probably need to use virtual inheritance. So you need to
> _learn_ about virtual inheritance if that's what you really want. It's the
> most difficult and problematic part of C++ (or any language that has
> virtual inheritance, I think).
>
> However, I have no idea why you want to inherit from Gtk::EventBox as well
> as Gtk::CellEditable. It would be best to avoid this.
>
>  
Well, like I said I've used cellrenderercustom example.

I guess, you know that Gtk::Entry has similar declaration:

class Entry
: public Widget,
 public Editable,
 public CellEditable
{...}

And Gtk::CellEditable is "interface" that allow to use entry when 
editing cell value (signals editing_done, remove_widget, etc) .
Also I need Gtk::EventBox to handle events and pack other widgets into 
it (actually, it may be any container widget).
Yes, I know about virtual inheritance, and gtkmm using it:

class Glib::Object : virtual public Glib::ObjectBase /* inherited in 
Gtk::EventBox */
{...}
class Glib::Interface : virtual public Glib::ObjectBase /* inherited in 
Gtk::CellEditable */
{...}

Now, when I've read the comments in objectbase.h file I've solved the 
problem - I have to call Glib::ObjectBase (typeid(MyClass)) in last 
derived class in my inheritance tree, then everything go well.

Murray, thank you for the hint that remind me where to start looking for 
problem :).

Regards,
-andrew