Re: boost::shared_ptr<T> and Gtk::TreeModelColumn<T>

[Paul Davis <paul linuxaudiosystems com>]

On Mon, 2006-09-18 at 23:08 +0200, Murray Cumming wrote:
> On Mon, 2006-09-18 at 16:26 -0400, Paul Davis wrote:
> > any opinions on the best way to have:
> > 
> > 	Gtk::TreeModelColumn<boost::shared_ptr<T> > 
> > 
> > at the moment, g++ appears to pick the void* partial specialization of
> > TreeModelColumn,
> 
> Are you sure that there is void* partial specialization? What exactly
> does it look like?

well, gdb let me know that this was going on, and the stack trace showed
we were in Value<void*> ... not really a partial specialization.

> >  which leads to problems later (glib complains that the
> > object is not actually a G_TYPE_POINTER etc). i have considered
> > implementing another partial specialization, but I am not sure it will
> > solve the issue. any thoughts?
> 
> It works for RefPtr and for other random types. TreeModelColumn should
> generate a custom gtype (via Glib::Value) to identify the type inside
> TreeView so you shouldn't get that warning theoretically.
> 
> A little test case might help us figure it out. You could try it with
> just a shared_ptr<int>, for instance.

i did that. it compiles but does not run. changing the shared_ptr<int>
back to just int corrects all issues. the behaviour is different than i
previously described, probably or possibly because of different versions
of gtkmm. i tried this code with 2.8 and got lots of errors of the form:

    unable to set property `text' of type `gchar array' from value of
    type 'glibmm__CustomBoxed_N5boost10shared_ptrIiEE'

--p



#include <boost/shared_ptr.hpp>

#include <gtkmm/main.h>
#include <gtkmm/window.h>
#include <gtkmm/treeview.h>
#include <gtkmm/liststore.h>

using namespace Gtk;
using namespace std;

int
main (int argc, char* argv[])
{
	Main app (&argc, &argv);

	Window win;
	TreeView view;
	struct Columns : public TreeModel::ColumnRecord {
	    Columns () { 
		    add (first);
		    add (second);
	    }
	    TreeModelColumn<bool> first;
	    TreeModelColumn<boost::shared_ptr<int> > second;
	};
	Columns columns;
	Glib::RefPtr<ListStore> model = ListStore::create (columns);

	view.set_model (model);
	view.append_column ("A", columns.first);
	view.append_column ("B", columns.second);
	view.set_headers_visible (true);
	view.set_size_request (100, -1);
	
	win.add (view);
	win.show_all ();
	
	for (int i = 0; i < 20; ++i) {
		TreeModel::Row child = *(model->append());
		child[columns.first] = i%2;
		child[columns.second] = boost::shared_ptr<int> (new int (i));
	}

	app.run ();
}