1 files changed, 49 insertions, 0 deletions
diff --git a/trunk/infrastructure/net.appjet.oui/dynamicvar.scala b/trunk/infrastructure/net.appjet.oui/dynamicvar.scala
new file mode 100644
index 0000000..b1f8c2e
--- /dev/null
+++ b/trunk/infrastructure/net.appjet.oui/dynamicvar.scala
@@ -0,0 +1,49 @@
+/**
+ * Copyright 2009 Google Inc.
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS-IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.appjet.oui;
+
+class NoninheritedDynamicVariable[T](init: T) {
+  private val tl = new ThreadLocal[T] {
+    override def initialValue = init.asInstanceOf[T with AnyRef]
+  }
+
+  /** Retrieve the current value */
+  def value: T = tl.get.asInstanceOf[T]
+  
+   
+  /** Set the value of the variable while executing the specified
+    * thunk.
+    *
+    * @param newval The value to which to set the fluid
+    * @param thunk The code to evaluate under the new setting
+    */
+  def withValue[S](newval: T)(thunk: =>S): S = {
+    val oldval = value
+    tl.set(newval)
+  
+    try { thunk } finally {
+      tl.set(oldval)
+    }
+  }
+
+  /** Change the currently bound value, discarding the old value.
+    * Usually <code>withValue()</code> gives better semantics.
+    */
+  def value_=(newval: T) = { tl.set(newval) }
+  
+  override def toString: String = "NoninheritedDynamicVariable(" + value  +")"
+}