Expression

An Expression object represents a primitive expression in which a single method is applied to a target and a set of arguments to return a result - as in "a.getFoo()".

In addition to the properties of the super class, the Expression object provides a value which is the object returned when this expression is evaluated. The return value is typically not provided by the caller and is instead computed by dynamically finding the method and invoking it when the first call to getValue is made.