Re: Gtk::TreeModel oddity

[Bob Caryl <bob fis-cal com>]

Murray Cumming wrote:

> On Wed, 2005-04-27 at 10:11 -0500, Bob Caryl wrote:
>  
>
> > Hello all,
> >
> > I have an application where I use a Gtk::ListStore in conjunction with a 
> > Gtk::TreeView to display representations of records in a database.  I 
> > have a function whereby the user can delete database records by clicking 
> > on one of those representations and pressing a button.  In the function 
> > connected to that button, I use the following code to remove the list 
> > store entry representing the deleted database record and to set the Tree 
> > View cursor:
> >
> >
> > Glib::RefPtr<Gtk::ListStore> list;                                // our 
> > listore object for the treeview
> > Glib::RefPtr<Gtk::TreeSelection> list_sel;                  // selection 
> > for the treeview
> >
> > Gtk::TreeModel::Path *path = new 
> > Gtk::TreeModel::Path(list->erase(list_sel->get_selected()));  // obtain 
> > path to the row following the deleted row
> >   
> >    
> I'd start by checking the result of get_selectd(), and the result of
> erase() for validity, with if(iter).
>
>  
>
> > if(path)   // if the path is valid set the view cursor to that path.
> > {
> >    tree->set_cursor(*path);
> >    delete path;
> > }
> >
> >
> > This code works (e.g. the row in the TreeView disappears and the cursor 
> > is repositioned on the following row), but I get several "Critical" 
> > messages:
> >
> > (gmwadmin:2454): Gtk-CRITICAL **: gtk_list_store_get_value: assertion 
> > `GTK_LIST_STORE (tree_model)->stamp == iter->stamp' failed
> >    
>
> This normally means that the iterator is from a different treemodel.
> Maybe you are using a different model here by mistake.
>
>  
>
> > (gmwadmin:2454): GLib-GObject-CRITICAL **: g_value_get_string: assertion 
> > `G_VALUE_HOLDS_STRING (value)' failed
> > (gmwadmin:2454): GLib-GObject-CRITICAL **: g_value_unset: assertion 
> > `G_IS_VALUE (value)' failed
> > (gmwadmin:2454): Gtk-CRITICAL **: gtk_list_store_get_path: assertion 
> > `iter->stamp == GTK_LIST_STORE (tree_model)->stamp' failed
> > (gmwadmin:2454): Gtk-CRITICAL **: gtk_tree_view_set_cursor_on_cell: 
> > assertion `path != NULL' failed
> >
> > Using the de-bugger I have determined that the call to "list->erase" is 
> > generating these messages.    The messages tend to make me think that 
> > the iterator returned by the Gtk::TreeSelection::get_selected function 
> > is not the same type of iterator required by the Gtk::ListStore::erase 
> > function as its formal parameter.  However, the docs don't seem to make 
> > a distinction between the iterators they describe as return values and 
> > formal parameters (in other words, following the hyperlinks in the docs 
> > to the iterators go to the same page).  I *think* I have implemented the 
> > foregoing code properly based on the gtkmm docs, but maybe I have not... 
> > can someone please point out my error?
> >
> > Best regards,
> > Bob Caryl
> > _______________________________________________
> > gtkmm-list mailing list
> > gtkmm-list gnome org
> > http://mail.gnome.org/mailman/listinfo/gtkmm-list
> >    
Ok... I am using only one view and one model so I think it's safe to 
rule out the possibility of the iterators being from different models. 

I have modified my code per your suggestion as follows:

Gtk::TreeModel::iterator iter1 = table_sel->get_selected();
if(iter1)
{
  Gtk::TreeModel::iterator iter2 = list->erase(iter);
  if(iter2)
  {
        Gtk::TreeModel::Path *path = new Gtk::TreeModel::Path(iter2);
        if(path)
       {
            tree->set_cursor(*path);
           delete path;
      }
  }
}

Running this code in the debugger shows that both "if(iter)" statements 
produce true results and the Gtk::ListStore::erasse function still 
produces the following critical messages:

(gmwadmin:2784): Gtk-CRITICAL **: gtk_list_store_get_value: assertion 
`GTK_LIST_STORE (tree_model)->stamp == iter->stamp' failed
(gmwadmin:2784): GLib-GObject-CRITICAL **: g_value_get_string: assertion 
`G_VALUE_HOLDS_STRING (value)' failed
(gmwadmin:2784): GLib-GObject-CRITICAL **: g_value_unset: assertion 
`G_IS_VALUE (value)' failed

Yet, the cursor still gets set properly in the View!!!   I suppose I can 
ignore these messages since  still get my cursor set.. but I am just 
paranoid about getting warnings when I compile me code, let alone 
CRITICAL messages.

Best regards,
Bob Caryl