From: jcore@...
Date: 2001-11-08T10:23:29+09:00
Subject: [ruby-talk:24621] ruby-gtk reference counting

I'm new to ruby-gtk (and Ruby for that matter) and I wonder why
ruby-gtk doesn't allow the programmer to do any reference counting.
Was this a deliberate design decision?

Here's the situation that I have where I need to manually access
the reference count of an object...  I have a variable list of
hboxes packed into a vbox containing notebook widgets.  When
notebooks are added/removed in order to maintain the tiled layout
I destroy all of the hboxes and recreate new ones.  The only problem
is that when the notebooks are removed from the hboxes they are
dereferenced and destroyed also.  Here's the relevant code:

def repack
  @connection_boxes.each {|b|
    b.each {|w|
      # w.ref
      b.remove(w)
    }
  @vbox.remove(b)
  }
  @connection_boxes.clear
  dim = Math.sqrt(@visible_connections.size).ceil
  pos = 0
  dim.times {
    box = Gtk::HBox.new(true, 0)
    @vbox.pack_start(box)
    @connection_boxes << box
    box.show
  }
  dim.times { # x direction
    0.upto(dim - 1) {|n| # y direction
      unless pos >= @visible_connections.size
	@connection_boxes[n].pack_start(@visible_connections[pos],
	true, true, 0)
        # @visible_connections[pos].unref pos += 1
      end
    }
  }
end

This code will fail with a message about Gtk::Object already being
destroyed.  My current solution for this is to patch ruby-gtk to
allow ref and unref calls to be made on an Object.  Is there a
better way to do this?  I would appreciate any help on the subject
and I've also included the patch that I made for the time being.

diff -ru gtk-0.25/src/rbgtkobject.c gtk-0.25.1/src/rbgtkobject.c
--- gtk-0.25/src/rbgtkobject.c	Sun Mar  4 04:22:36 2001
+++ gtk-0.25.1/src/rbgtkobject.c	Mon Nov  5 13:00:25 2001
@@ -497,6 +497,20 @@
     rb_raise(rb_eTypeError, "can't clone %s", rb_class2name(CLASS_OF(self)));
 }
 
+static VALUE
+gobj_ref(self)
+    VALUE self;
+{
+    gtk_object_ref(get_gobject(self));
+}
+
+static VALUE
+gobj_unref(self)
+    VALUE self;
+{
+    gtk_object_unref(get_gobject(self));
+}
+
 void Init_gtk_object()
 {
     gObject = rb_define_class_under(mGtk, "Object", rb_cObject);
@@ -551,6 +565,8 @@
     rb_define_method(gObject, "==", gobj_equal, 1);
     rb_define_method(gObject, "inspect", gobj_inspect, 0);
     rb_define_method(gObject, "clone", gobj_clone, 0);
+	 rb_define_method(gObject, "ref", gobj_ref, 0);
+	 rb_define_method(gObject, "unref", gobj_unref, 0);
 
     /* child initialize */
     Init_gtk_data();