extracting method name from linq expression

How can I get the name of the first method called from an expression in C#? Something like the fictional MethodUtils.NameFromExp开发者_运维百科ression() below:

Expression<Action<string>> expr = s => s.Trim();
Assert.AreEqual("Trim", MethodUtils.NameFromExpression(expr));

Ideally any util method would be written/overloaded in such a way that it could take expressions for any of the Action or Func delegate types.

Thanks in advance.

UPDATE

I found an answer (below) but would still like input as to whether this is a good solution or whether there already exists a way of doing this in the BCL.

A bit of digging with the debugger and I've answered my own question:

public static class MethodUtils
{
    public static string NameFromExpression(LambdaExpression expression)
    {
        MethodCallExpression callExpression = 
            expression.Body as MethodCallExpression;

        if(callExpression == null)
        {                
            throw new Exception("expression must be a MethodCallExpression");
        }

        return callExpression.Method.Name;
    }
}

Any comments on this implementation?