I've got a gtkmm program that includes a custom container (MyContainer)
including a function MyContainer::Clear, that needs to remove all
widgets from the container.
The implementation I have come up, which seems to work correctly for
Gtk::Widgets that are both Gtk::manage'd and otherwise, with looks like
this:
void MyContainer::Clear()
{
for (vector<Gtk::Widget *>::iterator i = mWidgets.begin();
i != mWidgets.end();
++i)
{
Gtk::Widget &w = (**i);
remove(w);
if (w.is_managed_())
{
w.unreference();
}
}
}
I've done a lot of digging to get this far. My decisions have been based
on the following assumptions:
- There is no precedent (no standard Gtk::Container has a function to
clear its child widgets) for this in gtkmm, I can't copy from anywhere.
- Widgets which are not manage()'d are never destroyed by
Gtk::Containers anywhere else, so they shouldn't be here either.
- Widgets which are manage()'d are explicitly reset to their initial
state by Gtk::Container::remove, and so should be explicitly unref'd.
- Gtk::Container::add and ::remove will not, under ordinary
circumstances, ever delete a widget (because widgets are instantiated
with an initial reference count of 1, and because of special removal of
manage()'d widgets)
For the record, my container's destructor is implemented this way:
MyContainer::~MyContainer()
{
forall_vfunc(false, (GtkCallback) gtk_widget_unparent, NULL);
}
I unparent each widget because that's what the custom container example
does:
https://developer.gnome.org/gtkmm-tutorial/stable/sec-custom-containers.html.en
Just for kicks, I changed the call 'remove(w)' in ::Clear to
'on_remove(w)' and removing the explicit unreference, and this seems to
work to maintain operational consistency with other gtkmm containers,
but I'm not sure that bypassing the call to ::remove is safe or correct,
though I understand why the call to ::on_remove (which unparents the
widget) is having the desired effect. Is it always safe to do this, or
are there circumstances where I accidentally bypass something important
this way?
Thanks,
Ryan
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