----- Original Message ---- From: Matt Hoosier <[EMAIL PROTECTED]> To: Richard <[EMAIL PROTECTED]> Cc: gtk-app-devel-list@gnome.org Sent: Sunday, November 26, 2006 6:44:13 PM Subject: Re: g_signal_connect_swapped
On 11/25/06, Richard <[EMAIL PROTECTED]> wrote: > > Could someone explain the reason for this function > > "g_signal_connect_swapped" > > I have read the manual here: > > http://www.gtk.org/tutorial/x159.html > > where it says: > > ,---- > | g_signal_connect_swapped() is the same as g_signal_connect() except that > | the instance on which the signal is emitted and data will be swapped > | when calling the handler. So when using this function to connect > | signals, the callback should be of the form > | > | > | void callback_func( gpointer callback_data, > | ... /* other signal arguments */ > | GtkWidget *widget); > | > | where the object is usually a widget. > `---- > > Could anyone express this a little clearer? I (as a gtk beginner) can > see no reason for it. This just means that the "widget" and "callback_data" pointers will be pushed onto the call stack in the opposite order from their ordering if hooked up with g_signal_connect(). If you're designing your own callback function, this probably isn't useful; just use g_signal_connnect() with a callback that has GObject* and gpointer parameters [in that order]. --------------------- I've used it for a couple of different things. One, if you aren't concerned with the widget that it is concerning, then you can used _swapped() and have your user_data first, and not worry about where the widget is, somewhere at the end of the argument list. Or another thing is with language bindings. I'm writing the language binding for pike, and in the signal marshaller I'm taking the arguments and actually rearranging them kind of different, so that the pike funciton gets the widget, the user_data, then an array of the rest of the arguments. This way the user can get the user_data at arg2, regardless of the number of other args there are. _______________________________________________ gtk-app-devel-list mailing list gtk-app-devel-list@gnome.org http://mail.gnome.org/mailman/listinfo/gtk-app-devel-list
