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From: coggins@rhodopsin.cs.unc.edu (Dr. James Coggins)
Newsgroups: comp.lang.c++
Subject: Re: are 'friend's really necessary ??
Message-ID: <12681@thorin.cs.unc.edu>
Date: 17 Mar 90 22:22:44 GMT
References: <169@pollux.kulcs.uucp> <133042@sun.Eng.Sun.COM>
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Reply-To: coggins@rhodopsin.cs.unc.edu (Dr. James Coggins)
Organization: University Of North Carolina, Chapel Hill
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In reply to the subject question, "No, but there are good reasons
for having them."

I don't like the friend examples where the reason for friend-ing
is to permit commutative usage of operators.  That strikes me as
a syntactic cure for certain kinds of laziness, but on the other
hand, such cures can sure be useful.

A better example of friend classes arises in my COOL library where I have
two classes that are separated for the purpose of isolating some
highly changeable junk from the main class definition, which is pretty
clean and understandable.  I make the classes friends and create
the junk class object in the constructor of the good class, providing
a pointer to the good object so the junk object knows what good object
it is associated with. 

That's the only pair of friend classes in my library, and I have no
friend functions at all.  

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Dr. James M. Coggins          coggins@cs.unc.edu
Computer Science Department   Questions: "How 'bout them HEELS?"
UNC-Chapel Hill               Correct response:
Chapel Hill, NC 27599-3175        "How 'BOUT them Heels?"
and NASA Center of Excellence in Space Data and Information Science
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