Re: newbie: on the form of callbacks...

[Davina Armstrong <davina lickey com>]

The argument that you pass through gtk_signal_connect() is the "data"
argument to the callback.  The other argument ("widget") is
automatically passed by GTK.  This is true of all the callback
prototypes.

Cevat Ustun wrote:
> Below are two snippets taken from the "Upgraded hello world"
> example in the tutorials. My question is:  the function
> "callback" is called with _one_ argument; a pointer to "button 1",
> whereas the callback function itself has _two_ arguments...
> What's going on?
>
> gtk_signal_connect (GTK_OBJECT (button), "clicked",
>                     GTK_SIGNAL_FUNC (callback),
>                     (gpointer) "button 1");
>
> void callback( GtkWidget *widget,
>                gpointer   data )
> {
> g_print ("Hello again - %s was pressed\n", (char *) data);
> }
>
> Thanks for any help,
>
> Cevat Ustun
>
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