Re: [gtkmm] RE: TreeView Model, SEGV on append - more info

[Martin Schulze <martin-ml hippogriff de>]

Am 2003.10.27 19:32 schrieb(en) "Ohrnberger, Erik":
> Everyone,
> 	I have a little bit more information on this.
>
> 	In the class that uses the TreeView, I have the following
> organization:
>
> Class is subclassed from Gtk::ScrolledWindow, and contains the
> following
> data members:
> 	Gtk::TreeView					tvMoldList;
> 	MoldListCols*					pCols;
> 	Glib::RefPtr<Gtk::ListStore>			pMoldListModel;
>
> In the class CTOR, I create the column instance (pCols) with a new.  I
> also
> create the model:
> 	pMoldListModel = ListStore::create( *pCols );
>
> Set the model to the treeview:
> 	tvMoldList.set_model( pMoldListModel );
>
> and then append the columns to the treeview:
> 	tvMoldList.append_column( "Icon", (*pCols).Icon );
>
> In the MoldListCols CTOR, I add it's columns:
> 	add( Icon ); ....
>
> In one of the class's methods, I want to add a single line to the
> model,
> however, by then the data member pMoldListModel returns a NULL, like
> it's
> lost scope or something.  Well, once I create another model, load all
> the
> items that should be in there and append line item that I wanted
> originally,
> it appears to work just fine.

The call
    pMoldListModel = ListStore::create( *pCols );
does indeed succeed and pMoldListModel is != 0 by then?

You do instantiate Gtk::Main before your ctor is executed?

There is no other call pMoldListModel = ... in your code?

pMoldListModel isn't hidden by a local variable?

You always operate on the same instance of your class?

Have you tried to allocate the TreeView dynamically
with Gtk::manage(new Gtk::TreeView) in your ctor?

What does tvMoldList.get_model() yield by the time
pMoldListModel is 0?

> It strikes me as strange that the model data member (pMoldListModel)
> would
> loose it's value between method calls.  You would think that it would
> maintain it's value so that you could manipulate the model for the
> lifetime
> of the object.
>
> What do you think?  Is this in fact the expected behavior of the
> TreeView,
> Gtk::ListStore classes?

No, absolutely not. RefPtr<> aquires a reference on the ListStore.
The ListStore will not be freed until the last reference has become
out of scope. You could try to assign pMoldListModel to a global
variable (so that two reference with a completely different scope
refer to the same ListModel) and see if anything changes.

I'm sorry, without a compilable example we can only do guesswork.

Regards,

  Martin