Path: utzoo!attcan!uunet!lll-winken!lll-tis!ames!pasteur!ucbvax!ulysses!hector!jss
From: jss@hector.UUCP (Jerry Schwarz)
Newsgroups: comp.lang.c++
Subject: Re: Friend specifier considered harmful
Message-ID: <10587@ulysses.homer.nj.att.com>
Date: 8 Sep 88 20:40:28 GMT
References: <61@cybaswan.UUCP> <8160@alice.UUCP> <29433@bbn.COM>
Sender: netnews@ulysses.homer.nj.att.com
Reply-To: jss@hector.UUCP (Jerry Schwarz)
Organization: AT&T Bell Laboratories
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My perspective on "friends" is that they are another C++ mechanism
for creating a public interface to a class.  As such, the
considerations that go into deciding whether to declare a friend are
essentially the same as those that go into deciding whether to
declare a public member.

There are two import distinctions between member functions and friend
functions.

        1.  Syntactic.  Friends are invoked using ordinary function
            notation rather member (. or ->) syntax.  Or in the case
            of friend operator, they may be invoked with the class
            object as the second operand.

        2.  A friend may be part of the interface of more than one
            class.

Both 1 and 2 may play a part in deciding to use a friend rather than
a member.

Jerry Schwarz
AT&T Bell Labs, Murray Hill