or mechanism provides more convenient and transparent API, it has its own drawbacks:
<OL>
<LI>It is not possible to check object class: it will return class of delegator and not 
class of target object itself
<LI>As delegator and target objects are two different objects, comparison of objects
references should be done with special care. 
<LI>Delegators adds extra space and processor overhead: instead of one object we have two and
each method invocation of field access requires extra delegator method call. 
