RE: [gtkmm] design question using libglademm

[Murray Cumming Comneon com]

Eric Bourque wrote:
> I've started converting an app I had which use to use the pre 
> gtk-2 versions of bakery, gtkmm, gnomemm, etc., and have 
> decided that using glade instead makes a lot of sense. There 
> are some things which are unclear to me after reading the 
> available documentation however, so I would appreciate 
> comments on what the 'preferred' methods are.

I assume that you are talking about libglademm rather than glademm.
> 
> Aggregate objects vs. derived objects?
> 
> I used to create new compound gui objects by deriving from 
> some existing gtkmm object, say a window, or vbox for 
> example. From an OO standpoint this made a lot of sense. 
> However, with glade, there is something with this approach 
> which is not clear to me. Suppose you create a glade file 
> which has a window with several other widgets in it. It seems 
> the normal approach is to reparent the glade window's 
> top-most child to the derived window class. The problem I 
> have found with this approach is that there is no way (that I 
> know of) to create just a vbox containing other widgets in 
> glade without using a placeholder window or dialog.

Yes. But you can choose to only instantiate a sub widget.

> This 
> means that after creating the Glade::Xml instance and 
> reparenting, there is still a blank window which shows up 
> unless you set the visible flag to 'no'.

I don't know why anybody would ever set the visible flag to 'yes'.

> Is that the correct 
> approach, or is there something simpler I've missed?

Yes, that's why I added the derived_widget stuff in libglademm 2.1/2.2.

> I guess the other approach is to not derive from an existing 
> gtkmm widget, but to simply let libglademm bring up the 
> window or dialog as well, and connect to slots in the 
> aggregate object. There is no need for reparenting this way, 
> but it doesn't seem as clean to me. I also don't see how to 
> properly 'destroy' windows this way (can you just call hide() 
> and assume everything is cleaned up when the 
> Glib::RefPtr<Gnome::Glade::Xml> goes out of scope during destruction?)
> 
> Any comments are appreciated.

I think you maybe haven't seen the new stuff in libglademm 2.1/2.2:
http://www.gtkmm.org/gtkmm2/docs/tutorial/html/ch19s03.html

There was some talk about that on this list a few weeks ago. Someone needs
to decide whether we need to improve it before we freeze it.

Murray Cumming
www.murrayc.com
murrayc usa net