add EventAttributeELResolver

improved invalid variable ex message

spring-binding/src/main/java/org/springframework/binding/expression/EvaluationAttempt.java

@@ -25,6 +25,7 @@ import org.springframework.core.style.ToStringCreator;
 public class EvaluationAttempt {
 
 	private Expression expression;
+
 	private Object context;
 
 	/**

spring-binding/src/main/java/org/springframework/binding/expression/EvaluationException.java

@@ -15,19 +15,17 @@
  */
 package org.springframework.binding.expression;
 
-import org.springframework.core.NestedRuntimeException;
-
 /**
  * Indicates an expression evaluation failed.
  * 
  * @author Keith Donald
  */
-public class EvaluationException extends NestedRuntimeException {
+public class EvaluationException extends RuntimeException {
 
 	/**
 	 * The evaluation attempt that failed. Transient because an EvaluationAttempt is not serializable.
 	 */
-	private transient EvaluationAttempt evaluationAttempt;
+	private EvaluationAttempt evaluationAttempt;
 
 	/**
 	 * Creates a new evaluation exception.
@@ -35,7 +33,17 @@ public class EvaluationException extends NestedRuntimeException {
 	 * @param cause the underlying cause of this exception
 	 */
 	public EvaluationException(EvaluationAttempt evaluationAttempt, Throwable cause) {
-		super(evaluationAttempt + " failed - make sure the expression is evaluatable in the context provided", cause);
+		this(evaluationAttempt, evaluationAttempt
+				+ " failed - make sure the expression is evaluatable in the context provided", cause);
+	}
+
+	/**
+	 * Creates a new evaluation exception.
+	 * @param evaluationAttempt the evaluation attempt that failed
+	 * @param cause the underlying cause of this exception
+	 */
+	public EvaluationException(EvaluationAttempt evaluationAttempt, String message, Throwable cause) {
+		super(message, cause);
 		this.evaluationAttempt = evaluationAttempt;
 	}
 

spring-binding/src/main/java/org/springframework/binding/expression/el/ELExpression.java

@@ -44,7 +44,9 @@ public class ELExpression implements Expression {
 		try {
 			Object result = valueExpression.getValue(ctx);
 			if (result == null && !ctx.isPropertyResolved()) {
-				throw new EvaluationException(new EvaluationAttempt(this, context), null);
+				EvaluationAttempt attempt = new EvaluationAttempt(this, context);
+				throw new EvaluationException(attempt, attempt
+						+ " failed: the expression path did not resolve--is the base variable incorrect?", null);
 			}
 			return result;
 		} catch (javax.el.PropertyNotFoundException e) {
@@ -59,7 +61,9 @@ public class ELExpression implements Expression {
 		try {
 			valueExpression.setValue(ctx, value);
 			if (!ctx.isPropertyResolved()) {
-				throw new EvaluationException(new SetValueAttempt(this, context, value), null);
+				SetValueAttempt attempt = new SetValueAttempt(this, context, value);
+				throw new EvaluationException(attempt, attempt
+						+ " failed: the expression path did not resolve--is the base variable incorrect?", null);
 			}
 		} catch (javax.el.PropertyNotFoundException e) {
 			throw new PropertyNotFoundException(new EvaluationAttempt(this, context), e);