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diff --git a/bundles/org.simantics.databoard/src/org/simantics/databoard/binding/reflection/UnionClassBinding.java b/bundles/org.simantics.databoard/src/org/simantics/databoard/binding/reflection/UnionClassBinding.java
new file mode 100644
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+++ b/bundles/org.simantics.databoard/src/org/simantics/databoard/binding/reflection/UnionClassBinding.java
@@ -0,0 +1,159 @@
+/*******************************************************************************
+ *  Copyright (c) 2010 Association for Decentralized Information Management in
+ *  Industry THTH ry.
+ *  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:
+ *      VTT Technical Research Centre of Finland - initial API and implementation
+ *******************************************************************************/
+package org.simantics.databoard.binding.reflection;
+
+import org.simantics.databoard.Bindings;
+import org.simantics.databoard.adapter.AdaptException;
+import org.simantics.databoard.binding.Binding;
+import org.simantics.databoard.binding.UnionBinding;
+import org.simantics.databoard.binding.error.BindingConstructionException;
+import org.simantics.databoard.binding.error.BindingException;
+import org.simantics.databoard.serialization.Serializer;
+import org.simantics.databoard.serialization.SpecializedSerializerProvider;
+import org.simantics.databoard.type.UnionType;
+
+/**
+ * Bindings an abstract class with @Union annotation to a DataBoard's UnionType.
+ * 
+ * Example of usage:
+ *  @Union({Rectangle.class, Circle.class, Triangle.class}) class Shape {}
+ *  	
+ *  class Rectangle extends Shape { public int width, height; }
+ *  class Circle extends Shape { public int radius; }		
+ *  class Triangle extends Shape { public int sideLength; }		
+ *
+ * @author Toni Kalajainen
+ */
+class UnionClassBinding extends UnionBinding implements SpecializedSerializerProvider {
+
+	Class<?>[] componentClasses;
+	Serializer specializedSerializer;
+	
+	public UnionClassBinding(UnionType type) 
+	throws BindingConstructionException {
+		this.type = type;
+	}
+	
+	@Override
+	public Object create(int tag, Object value) {
+		return value;
+	}
+
+    @Override
+    public void setValue(Object union, int tag, Object value)
+	throws BindingException {
+    	if (tag != getTag(union)) throw new BindingException("Cannot change the class of an instance");
+    	Binding cb = getComponentBinding(tag);
+    	cb.readFrom(cb, value, union);
+    }
+	
+	@Override
+	public int getTag(Object obj) throws BindingException {
+		for (int i=0; i<componentClasses.length; i++)
+			if (componentClasses[i].isInstance(obj)) return i;
+		throw new BindingException(obj.getClass().getSimpleName()+" is not a known component class");
+	}
+	@Override
+	public Object getValue(Object obj) {
+		return obj;
+	}
+	@Override
+	public boolean isInstance(Object obj) {
+		for (Class<?> c : componentClasses) 
+			if (c.isInstance(obj)) return true;					
+		return false;
+	}
+
+    @Override
+    public Serializer getSpecializedSerializer() {
+        return specializedSerializer;
+    }
+
+
+	transient Boolean isImmutable;
+	
+	@Override
+	public synchronized boolean isImmutable() {
+		if ( isImmutable == null ) {
+			boolean b = true;
+			for ( Binding cb : getComponentBindings() ) {
+				b &= cb.isImmutable();
+				if (!b) break;
+			}
+			isImmutable = b;
+		}
+		return isImmutable;
+	}
+
+	@Override
+    public Object readFromTry(Binding srcBinding, Object src, Object dst) throws BindingException
+    {
+		UnionBinding sb = (UnionBinding) srcBinding;
+		int st = sb.getTag(src);
+		int dt = getTag(dst);
+		Binding scb = sb.getComponentBinding(st);
+		Object sv = sb.getValue(src);
+		
+		
+		if (st==dt) {
+			// Same Tag
+			Object dv = getValue(dst);
+			Binding dcb = getComponentBinding(dt);
+			dcb.readFrom(scb, sv, dv);
+			return dv;
+		} else {
+			// Different Tag -> return cloned or (same, if immutable) value
+			try {
+				Binding dcb = getComponentBinding(st);
+				return Bindings.adapt(src, scb, dcb);
+			} catch(AdaptException e) {
+				throw new BindingException(e);
+			}
+		}
+		
+	}	
+	
+	/**
+	 * Returns true if the tag of this union type can be modified
+	 *  
+	 * @return
+	 */
+	public boolean isTagMutable() {
+		return true;
+	}
+ 
+	@Override
+	protected boolean baseEquals(Object obj) {
+		if (!super.baseEquals(obj)) return false;	
+
+		UnionClassBinding o = (UnionClassBinding)obj;
+		if (isImmutable != o.isImmutable) return false;
+		if (specializedSerializer != o.specializedSerializer) return false;
+		if (componentClasses.length != o.componentClasses.length) return false;
+		
+		for (int i = 0; i < componentClasses.length; i++) {
+			if (!componentClasses[i].equals(o.componentClasses[i]))
+				return false;
+		}
+		
+		return true;
+	}
+	
+	@Override
+	public int baseHashCode() {
+		int code = super.baseHashCode();
+		for (int i = 0; i < componentClasses.length; i++)
+			code = 23 * code + componentClasses.hashCode();
+		
+		return code;
+	}
+}