On 3/11/08, Armin Burgmeier <[EMAIL PROTECTED]> wrote: > I believe the current implementation of Item::get_items_at is wrong: > > #m4 _CONVERSION(`GList*',`Glib::ListHandle< Glib::RefPtr<Item> >',` > $2($3, Glib::OWNERSHIP_NONE)') > > _WRAP_METHOD(Glib::ListHandle< Glib::RefPtr<Item> > get_items_at(double > x, double y, const Cairo::RefPtr<Cairo::Context>& context, bool > is_pointer_event, bool parent_is_visible, Glib::ListHandle< > Glib::RefPtr<Item> >& found_items), goo_canvas_item_get_items_at) > > Since the ownership of the returned ListHandle is set to NONE, the > actual GList* will be leaked. However, if we set shallow ownership, then > we get memory corruption because in the C API, the returned GList* is > meant to be the same as the one passed in, with perhaps some items added > to the front and thus returning a new list head. > > If I get it right, then the ownership of the found_items ListHandle > needs to be set to none, and a new ListHandle with shallow ownership > needs to be returned. We can't do this though, probably, because the > ownership of the ListHandle is private. > > I think the C++ way to handle this is to use an insert iterator such as > > template<typename InsertIter> > InsertIter get_items_at(double x, double y, const > Cairo::RefPtr<Cairo::Context>& context, bool is_pointer_event, bool > parent_is_visible, InsertIter iter); > > to be used like this: > > std::vector<Glib::RefPtr<Item> > items; > some_item->get_items_at(..., std::inserter(items, items.end())); > > This is also more powerful because items can be inserted anywhere > instead of just at the beginning. However, I don't think other *mm > projects do anything similar, which is why I am asking for opinions > first. > > The corresponding vfunc still needs special consideration then, since > virtual functions cannot be templatized. Probably it is enough to just > pass a specific container, such as std::vector, since the only code > calling it is goocanvasmm itself anyway. > > Any opinions? Do you think it is OK to change it this way, or do you > have other ideas to tackle this? > > Armin
I haven't had time to read this proposal thoroughly yet, but I just wanted to mention that when I was wrapping this function originally, I thought it felt like a pretty poor API at the C level. So maybe it would be best to try to improve the API at the C level before attempting workarounds in the wrapper. That said, I'll try to read your proposal more thoroughly when I get a little more time and offer comments as well. -- jonner _______________________________________________ gtkmm-list mailing list [email protected] http://mail.gnome.org/mailman/listinfo/gtkmm-list
