Re: [gtk-list] Freeing data connected to a widget via signals...

[Thomas Mailund <mailund mail1 stofanet dk>]

>>>>> "M" == Matthew D Allen <s2mdalle@titan.vcu.edu> writes:

 M> Let's say I have:

 M> typedef struct{
 M>    char *some_dyn_allocd_mem;
 M>    char *some_more_mem
 M>    struct other_structure *ptr;   /* Contains further nested pointers */
 M> } foobar;

 M> and then I create a dynamically allocated foobar (with some
 M> subfields that are dynamically allocated) - call it "ptr"

 M> then I do:

 M> gtk_signal_connect(GTK_OBJECT(my_button), "clicked",
 M>                    GTK_SIGNAL_FUNC(my_button_callback), ptr);

 M> How do I know if "ptr" will be correctly freed when the widget
 M> gets destroyed?

It won't.  GTK wouldn't know how to.

 M> How do I attach a "rider" onto the destroyed signal so that I can
 M> do a custom free routine on the object data when the widget gets
 M> destroyed?

 M> I tried gtk_signal_connect_after(GTK_OBJECT(my_button), "destroy",
 M>                                  GTK_SIGNAL_FUNC(my_custom_foobar_free) ptr);

 M> but it never seems to get called.

hmm, no, there's something about emission of hooks on GTK_DESTROYED
objects, but quite remember what it was.  Someone more enlightened
might clear this up.

 M> I can't imagine GTK+ knows how to free the fields in my custom
 M> data structure, yet at the same time, I don't know how to do it
 M> myself.

 M> Anybody have an idea how I can do that?

take a look at

  guint       gtk_signal_connect_full         (GtkObject *object,
                                               const gchar *name,
                                               GtkSignalFunc func,
                                               GtkCallbackMarshal marshal,
                                               gpointer data,
                                               GtkDestroyNotify destroy_func,
                                               gint object_signal,
                                               gint after);

where GtkDestroyNotify is

  void        (*GtkDestroyNotify)             (gpointer data);

it's this guy you want to use.  The destroy_func is called when the
signal is removed.

        /mailund