Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!mcnc!thorin!unc!steele
From: steele@unc.cs.unc.edu (Oliver Steele)
Newsgroups: comp.lang.c++
Subject: Re: References considered crippled
Message-ID: <8501@thorin.cs.unc.edu>
Date: 14 Jun 89 23:38:17 GMT
References: <NEATH.89Jun12170832@solar-1.stars.flab.Fujitsu.JUNET> <6361@columbia.edu> <9483@alice.UUCP> <6362@columbia.edu>
Sender: news@thorin.cs.unc.edu
Reply-To: steele@unc.cs.unc.edu (Oliver Steele)
Distribution: comp.lang.c++
Organization: University Of North Carolina, Chapel Hill
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kearns@read.UUCP () writes:
>(1) Why use a->b instead of (*c).b?  The reason is that (*c).b is ugly
>and hard to type.  If we had reassignable references, a ptr that is
>usually dereferenced, like c, could be declared as a reference cref,
>so we could write cref.b instead.  The few times we don't want to
>derefence could be handled with the cref& notation.

Do you need reassignable references for this?  It might be simpler to
recognize a.b and a->b as synonymous; in fact, a->b could stand for
(**a).b, (***a).b, ..., as well as for (*a).b, making code that dealt
with Macintosh Handle's, for instance, much easier to read.  There's
never any ambiguity at compile time as to whether something has fields
itself or is a pointer to something that does, and introducing the
synonymity doesn't break existing code.

The disadvantage of such a scheme is that you can't tell the cost of
an expression from looking at it, unless you scan backward for an
declaration.  You might not think to declare a temporary variable to
rewrite a block of code making lots of references to fields of a, but
if the code instead referred to fields of (***a) you might wrap it
in {register foo *pa = **a; ...} and refer to fields of (*pa) instead.
And until optimizing compilers are more common-place, it will be more
important to some people that computationally expensive code look
expensive, than that conceptually simple code look simple.

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 Oliver Steele					  ...!decnet!mcnc!unc!steele
 UNC-CH Linguistics					   steele@cs.unc.edu