New class to make attribute change listening more convenient in action script

git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@5329 542714f4-19e9-0310-aa3c-eee0fc999fb1

src/as/com/threerings/presents/dobj/AttributeChangeAdapter.as

@@ -0,0 +1,46 @@
+//
+// $Id$
+//
+// Narya library - tools for developing networked games
+// Copyright (C) 2002-2007 Three Rings Design, Inc., All Rights Reserved
+// http://www.threerings.net/code/narya/
+//
+// This library is free software; you can redistribute it and/or modify it
+// under the terms of the GNU Lesser General Public License as published
+// by the Free Software Foundation; either version 2.1 of the License, or
+// (at your option) any later version.
+//
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public
+// License along with this library; if not, write to the Free Software
+// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+package com.threerings.presents.dobj {
+
+/**
+ * Attribute change listener that delegates the event handling to a free function.
+ */
+public class AttributeChangeAdapter implements AttributeChangeListener
+{
+    /**
+     * Creates a new listener that calls the given function when the attribute changes.
+     */
+    public function AttributeChangeAdapter (fn :Function)
+    {
+        _fn = fn;
+    }
+
+    /** @inheritDoc */
+    // from AttributeChangeListener
+    public function attributeChanged (event :AttributeChangedEvent) :void
+    {
+        _fn(event);
+    }
+
+    protected var _fn :Function;
+}
+}