Re: Must widgets stay in context?

[rob page <page rob gmail com>]

My understanding is that managed widgets are freed when their parent widget is.

Rob.

On 14/12/05, R. Douglas Barbieri <dooglio gmail com> wrote:
> Exactly. You have a choice: you manage the lifetime of your widgets
> (your own heap management or via the stack), or let GTK do it. :-)
>
> A question regarding this: does GTK have some sort of
> garbage-collection management, or are all of the "manage()"ed widgets
> finally freed at runtime?
>
> On 12/14/05, rob page <page rob gmail com> wrote:
> > I believe you want to be using Gtk::manage
> >
> > advbox->add(*Gtk::manage(new class Gtk::Label(_("Misc Settings"))));
> >
> > (code ripped from one of my programs)
> >
> > which should be much easier to use dynamically.
> >
> > Rob.
> >
> > On 14/12/05, Karen Pease <meme daughtersoftiresias org> wrote:
> > > Hi - I'm new to gtkmm, and still just starting to get my feet wet.  I'm a bit
> > > confused by something and can't find information in the documentation about
> > > it - namely, must widgets stay in context after they're added to a container?
> > > gtkmm forbids, say:
> > >
> > > some_frame.add(Gtk::Label("Test"));
> > >
> > > because it wants a Gtk::Label&, not a Gtk::Label.  Most sample code that I've
> > > seen have a member variable (say, m_label_test) used like:
> > >
> > > SomeClass::SomeClass() : m_label_test("Test")
> > > {
> > >    some_frame.add(Gtk::Label("Test"));
> > > }
> > >
> > > This seems to suggest to me that gtk cares whether the widget goes out of
> > > context or not - that it's not copying the widget that I gave it, but
> > > referencing it by pointer.  And thus, it would seem to suggest that this is
> > > unacceptable:
> > >
> > > some_function()
> > > {
> > >     Gtk::Label label_test("Test");
> > >     some_frame.add(label_test);
> > > }
> > >
> > > If I am correct in this, then how do I deal with a situation in which what
> > > widgets are used is dynamic?  In my application, I have an information frame
> > > which can display information about any one of a wide range of possible
> > > objects in a scene, and each object will display different kinds of
> > > information about itself (it's not the same type of information between
> > > different objects - a wire may list its current, voltage, resistance,
> > > conductor material, conductor diameter, etc; a vehicle may list its velocity,
> > > wind resistance, drag coefficient, G-forces, mass, etc).
> > >
> > > Do I have to have a member variable widget for every last label possibility
> > > even though at any given time the vast majority of them will be unused?  That
> > > would be a pain, at least as far as labels go.  I tried creating
> > > std::vector<Gtk::Label> label_list to store any widgets that got created, but
> > > that didn't work.  Gtk::Label's copy constructor is private, so
> > > label_list.push_back(Gtk::Label(text)) fails.  Right now I'm using a
> > > roundabout hack, using a std::vector<Gtk::Label*>, filling it with
> > > label_list.push_back(new Gtk::Label(text)), deferencing the pointers when I
> > > add them to the frame, and using a cleanup function that deallocates
> > > everything in label_list when it is no longer used.  Needless to say, this is
> > > ugly.  Is there a better way?
> > >
> > > Thanks for your help!
> > >
> > >         - Karen
> > >
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> > >
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> >
>
>
> --
> R. Douglas Barbieri
> doug dooglio net
>