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From: Robert A Duff <bobduff@shell01.TheWorld.com>
Newsgroups: comp.lang.ada
Subject: Re: Dereferencing and style guides
Date: Fri, 11 Oct 2013 08:52:59 -0400
Organization: The World Public Access UNIX, Brookline, MA
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Date: 2013-10-11T08:52:59-04:00
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Bill Findlay <yaldnif.w@blueyonder.co.uk> writes:

> Can I make the contrary case?

Certainly.

> Given that we know that P is a pointer, P.f or P(i) can only reasonably be
> interpreted as dereferencing P and selecting a component from the result; so
> I do not see that P^.f or P^(i) improves comprehensibility to any
> significant degree.
>
> Given that we do not know that P is a pointer, P.f or P(i) is essentially
> the same cognitive burden as R.f or A(i); from the uniform referent point of
> view this is an advantage.  It fails to be, only if the dereference fails,
> and we know that that should not happen in Ada 8-).  Even if it does, the
> extra effort of perceiving the semantics correctly is trivial.

By "dereference fails", I assume you're talking about null pointers.
I wasn't so worried about that -- I'm more worried about
aliasing.  I'm thinking "X^.Y := ..." is a helpful reminder that
some other pointers might also point to X^.

So I'm not convinced.  But I guess your point of view is more
popular than mine.  Consider languages like Java, for ex,
where (almost) everything is a pointer, greatly (IMHO) exacerbating
the aliasing problem.

A pure functional language would be different: there, the semantics
of "a thing" and "a pointer to a thing" are indistinguishable,
so there's no reason to have explicit dereference operators.

- Bob