diff -r d6224d602145 -r 1cd7d8af99ba nashorn/src/jdk.scripting.nashorn/share/classes/jdk/nashorn/api/scripting/DefaultValueImpl.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/nashorn/src/jdk.scripting.nashorn/share/classes/jdk/nashorn/api/scripting/DefaultValueImpl.java	Fri Feb 20 15:47:28 2015 +0100
@@ -0,0 +1,55 @@
+/*
+ * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code 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 General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package jdk.nashorn.api.scripting;
+
+import jdk.nashorn.internal.runtime.JSType;
+
+/**
+ * Default implementation of {@link JSObject#getDefaultValue(Class)}. Isolated into a separate class mostly so
+ * that we can have private static instances of function name arrays, something we couldn't declare without it
+ * being visible in {@link JSObject} interface.
+ */
+class DefaultValueImpl {
+    private static final String[] DEFAULT_VALUE_FNS_NUMBER = new String[] { "valueOf", "toString" };
+    private static final String[] DEFAULT_VALUE_FNS_STRING = new String[] { "toString", "valueOf" };
+
+    static Object getDefaultValue(final JSObject jsobj, final Class<?> hint) throws UnsupportedOperationException {
+        final boolean isNumber = hint == null || hint == Number.class;
+        for(final String methodName: isNumber ? DEFAULT_VALUE_FNS_NUMBER : DEFAULT_VALUE_FNS_STRING) {
+            final Object objMember = jsobj.getMember(methodName);
+            if (objMember instanceof JSObject) {
+                final JSObject member = (JSObject)objMember;
+                if (member.isFunction()) {
+                    final Object value = member.call(jsobj);
+                    if (JSType.isPrimitive(value)) {
+                        return value;
+                    }
+                }
+            }
+        }
+        throw new UnsupportedOperationException(isNumber ? "cannot.get.default.number" : "cannot.get.default.string");
+    }
+}