--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/org.eclipse.core.databinding.observable/src/org/eclipse/core/databinding/observable/value/WritableValue.d	Tue Apr 21 10:55:51 2009 +0200
@@ -0,0 +1,113 @@
+/*******************************************************************************
+ * Copyright (c) 2006, 2007 IBM Corporation and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *     IBM Corporation - initial API and implementation
+ *     Brad Reynolds - bug 158687
+ *     Brad Reynolds - bug 164653, 147515
+ *******************************************************************************/
+
+package org.eclipse.core.databinding.observable.value;
+
+import org.eclipse.core.databinding.observable.Diffs;
+import org.eclipse.core.databinding.observable.Realm;
+
+/**
+ * Mutable (writable) implementation of {@link IObservableValue} that will maintain a value and fire
+ * change events when the value changes.
+ * <p>
+ * This class is thread safe. All state accessing methods must be invoked from
+ * the {@link Realm#isCurrent() current realm}. Methods for adding and removing
+ * listeners may be invoked from any thread.
+ * </p>
+ * @since 1.0
+ */
+public class WritableValue : AbstractObservableValue {
+
+    private final Object valueType;
+
+    /**
+     * Constructs a new instance with the default realm, a <code>null</code>
+     * value type, and a <code>null</code> value.
+     */
+    public this() {
+        this(null, null);
+    }
+
+    /**
+     * Constructs a new instance with the default realm.
+     * 
+     * @param initialValue
+     *            can be <code>null</code>
+     * @param valueType
+     *            can be <code>null</code>
+     */
+    public this(Object initialValue, Object valueType) {
+        this(Realm.getDefault(), initialValue, valueType);
+    }
+
+    /**
+     * Constructs a new instance with the provided <code>realm</code>, a
+     * <code>null</code> value type, and a <code>null</code> initial value.
+     * 
+     * @param realm
+     */
+    public this(Realm realm) {
+        this(realm, null, null);
+    }
+
+    /**
+     * Constructs a new instance.
+     * 
+     * @param realm
+     * @param initialValue
+     *            can be <code>null</code>
+     * @param valueType
+     *            can be <code>null</code>
+     */
+    public this(Realm realm, Object initialValue, Object valueType) {
+        super(realm);
+        this.valueType = valueType;
+        this.value = initialValue;
+    }
+
+    private Object value = null;
+
+    public Object doGetValue() {
+        return value;
+    }
+
+    /**
+     * @param value
+     *            The value to set.
+     */
+    public void doSetValue(Object value) {
+        bool changed = false;
+
+        if (this.value is null && value !is null) {
+            changed = true;
+        } else if (this.value !is null && !this.value.equals(value)) {
+            changed = true;
+        }
+
+        if (changed) {
+            fireValueChange(Diffs.createValueDiff(this.value, this.value = value));
+        }
+    }
+
+    public Object getValueType() {
+        return valueType;
+    }
+
+    /**
+     * @param elementType can be <code>null</code>
+     * @return new instance with the default realm and a value of <code>null</code>
+     */
+    public static WritableValue withValueType(Object elementType) {
+        return new WritableValue(Realm.getDefault(), null, elementType);
+    }
+}