Path: utzoo!mnetor!uunet!husc6!uwvax!oddjob!nucsrl!morrison
From: morrison@eecs.nwu.edu (Vance Morrison)
Newsgroups: comp.lang.c++
Subject: Re: Why doesn't c++ allow overloading member operators?
Message-ID: <8180005@eecs.nwu.edu>
Date: 17 Mar 88 19:24:59 GMT
References: <11778@sri-spam.istc.sri.com>
Organization: Northwestern U, Evanston IL, USA
Lines: 30


    The question is "why doen't c++ allow you to overload the "." operator.

    I asked myself this very question and I don't have a good reason, but
I did realise that the "." operator is fundamentally different from most
other operators.  Namely its right operand MUST BE A COMPILE TIME CONSTANT
DEFINED FOR THAT PARTICULAR CLASS/STRUCTURE.  I don't believe that this
is the case with any other operator.  

    In order for c++ to alow "mimicking" of this operator's semantics,
(which is what all good overloaded operations do) there has to be a facility
in c++ to access this compile time info.  This opens up a whole new set
of problems which are better thought out carefully first.

    The real reason you probably want overloading is to allow "controled
access" to instance variables.  What would meet this need without overloading
the "." is for c++ to REDEFINE the "." operator for the class EXAMPLE so

	example.member 		means 	example.member()

    and if example.member() does not exist, then the "." means what it
used to.  I know for a fact that AT&T c++ does NOT allow member fuctions
and member variables to have the same name so this would not break any
code.

	SO HOW ABOUT IT??


					Vance Morrison
					morrison@accuax.nmu.edu