if (!Field.class.isInstance(fieldAsObject))
throw new TapestryException(BindingsMessages.validateBindingForFieldsOnly(component),
location, null);
Field field = (Field) fieldAsObject;
// The expression is a validator specification, such as "required,minLength=5".
// ValidatorBindingFactory is the odd man out becasuse it needs the binding component (the
// component whose parameter is to be bound) rather than the containing component, the way
// most factories work.