Xref: utzoo comp.lang.c++:11948 comp.std.c++:656
Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!helios!bcm!dimacs.rutgers.edu!seismo!uunet!world!decwrl!apple!netcom!sjsumcs!horstman
From: horstman@mathcs.sjsu.edu (Cay Horstmann)
Newsgroups: comp.lang.c++,comp.std.c++
Subject: Re: distinguishing operator[] on left and right
Message-ID: <1991Mar2.000705.3496@mathcs.sjsu.edu>
Date: 2 Mar 91 00:07:05 GMT
References: <1991Feb28.212419.20920@ndl.com>
Organization: San Jose State University - Math/CS Dept.
Lines: 23

In article <1991Feb28.212419.20920@ndl.com> gilley@ndl.com (Greg Gilley) writes:
>Is there any way to distinguish when the operator[] is used as an
>lvalue as opposed to an rvalue?
>
Surely I am not the first one to propose this one, but here goes anyway.

Just as pre- and postincrement operator++ are distinguished by a hidden
int argument, could this not be done for lvalue and rvalue operator[]?

I.e. const X& operator[]( int ) and X& operator[]( int, int )?

The second int is always 0. 

If the second operator is not present, the first one is taken for both
lvalues and rvalues. 

Points to consider:
   (1) It is ugly as hell
   (2) It has precedent (operator++)
   (3) It won't break existing code
   (4) It does not use the keyword "static" in unusual ways.

Cay