Path: utzoo!attcan!uunet!mcvax!cernvax!ethz!marti
From: marti@ethz.UUCP (Robert Marti)
Newsgroups: comp.lang.c++
Subject: Re: "Inheritance" of operator=()
Summary: "inherited" assignment does make sense
Keywords: user error or cfront error?
Message-ID: <933@ethz.UUCP>
Date: 17 May 89 16:18:06 GMT
References: <863@ethz.UUCP> <11519@ulysses.homer.nj.att.com>
Organization: ETH Zuerich
Lines: 30

In article <11519@ulysses.homer.nj.att.com>, jss@hector.UUCP (Jerry Schwarz)
writes:
> Assignment is special because it is defined for all classes, (thus it
> never needs to be inherited).
> 
> But the meaning of assignment has changed between 1.2 and 2.0. In 1.2
> the synthesized assignment operator was always "bitwise copy".  This
> was seen to be wrong and in 2.0 assignment is defined to be
> "recursive".

I am glad to hear that the semantics of (user-defined) assignment has
changed in 2.0, although I am not quite sure what you mean when you say
that it is defined to be "recursive".  Could you elaborate on that?


> Note that it doesn't make much sense to just "inherit" assignment
> because that would mean that the added members of D wouldn't
> participate in assignment of D.  Since 1.2 didn't implement a
> "recursive" assignment, and a bitwise copy would clearly be wrong.
                          ^^^^^
                          seems superfluous to me(?)

Well, in my example, no additional data members were defined in the
derived class, so bitwise copy would definitely make sense!

-- 
Robert Marti                      Phone:      +41 1 256 52 36
Institut fur Informationssysteme
ETH-Zentrum                       CSNET/ARPA: marti%inf.ethz.ch@relay.cs.net
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