Re: [java-gnome-hackers] Adding switch-page signal

[Andrew C. <an...@op...>]

On Sun, 2009-02-15 at 13:55 +0100, Stefan Schweizer wrote:
> On Sat, 2009-02-14 at 22:03 +1100, Andrew Cowie wrote:
> > That _might_ work. I kinda doubt it, actually, but it might do as a
> > kludge. A patch bundle to this effect is attached.
> 
> Unfortunately changing the parameter to glong did not work. I get a
> "java.lang.NoSuchMethodError: receiveSwitchPage" when connecting to the
> signal.

Do you have a TestCase that runs through this? 

testReactingToCursorPositionChanges() in ValidateTextBuffer is an
example of hooking up a signal that reacts to a programmatic event. If
you coded up something like that and sent us a bundle with it, then we
could see what you're seeing.

As for the NoSuchMethodError, that is what happens when the signature
doesn't precisely match. Java VMs are very precise that way. You might
have had something incorrect on the other side.

If you manually remove the comments hiding lines 521-522 in
src/jni/bindings_java_signal.c you'll see some debug info about this.

For example, GtkWidget.receiveDeleteEvent() is invoked with a signature
of

(Lorg/gnome/glib/Signal;JJ)Z

with the first J being the long for the pointer address of Widget
"source", and the second J being the long for the boxed Event "event". I
imagine you'll find it will attempt to find a method called
receiveSwitchPage() with a signature of

(Lorg/gnome/glib/Signal;JJI)V

if you change to glong like I suggested. So then the question would be
why the generated receiver method doesn't have a matching signature.

Actually, the real question is what *actually* it is being invoked as
(since you can't change what GLib thinks the parameters are); presumably
it's not what I speculated above since presumably having changed that
parameter to glong would have caused a receive of that signature no
problem.

Once you find out what is actually being composed, then can you come up
with something else for the .defs data that you can cause the signature
of the generated receiveSwitchPage() to match. Should be fairly straight
forward once you know what it's feeding you.

AfC
Sydney