Re: Glib -> GList

["MET @ Uber" <met uberstats com>]

On Wednesday 01 January 2003 12:48 am, James M. Cape wrote:
> On Tue, 2002-12-31 at 23:21, MET @ Uber wrote:
> > I'm trying without any luck to find documentation on using GList in a
> > situation with more than one node.  I know that it's basic structure
> > contains a 'next' pointer and a void pointer called 'data'.  While
> > researching it I read something about using the void data pointer to be
> > able to point to anything such as another structure, but I haven't found
> > any examples.  This email proves that I am not a very experienced
> > programmer, so using a void pointer to me is brand new.  Any suggestions
> > or links to suggestions on using GList with my own data (as it appears to
> > be great) would be very appreciated.
> >
> > Thanks in advance,
> >
> > ~ Metnetsky
>
> A void pointer just means an untyped pointer, or a pointer to anything.
>
> Typically you use the "data" member of a GList/GSList when you want to
> retrieve the data from a list item:
>
> Example:
>
> GList *list = NULL;
> gchar *str = "some string";
>
> list = g_list_append (list, str);
>
> g_message ("The contents of the first node in list is \"%s\".", (gchar
> *) (list->data));
>
> This creates a new GList item with the data set to str ("some string"),
> and appends it the end of the (empty) GList, "list".
>
> The g_message output would be:
>
> some-app (pid) Message: The contents of the first node in list is "some
> string".
>
> Since it's a void pointer, you can store anything you want as the data,
> like GtkWidgets, your own structs, ints (using GINT_TO_POINTER()), etc.
>
> Basically, rather than creating a new list type for every data type you
> want to store, doing it with a gpointer means you can re-use the same
> code for anything (though it also means that it's a good idea to see if
> the contents of "data" are valid before doing anything, and it also
> means deep freeing the list is not as simple as g_list_free()).

I was wondering if you, or anyone else could explain how to use the data void 
pointer in GList to point to another structure.  Any kind of structure would 
do, the simpler the better I'd imagine.  Thanks in advance, and I hope this 
isn't something too complicated to email.  Oh, if you know of a site that has 
this in some tutorial/example/documentation form that would be perfect too.

~ Metnetsky