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From: brnstnd@kramden.acf.nyu.edu (Dan Bernstein)
Newsgroups: comp.lang.misc
Subject: Re: Answers, Chapter 2: to point or not to point
Message-ID: <7006:Nov620:42:3990@kramden.acf.nyu.edu>
Date: 6 Nov 90 20:42:39 GMT
References: <1622:Nov606:57:0190@kramden.acf.nyu.edu> <5073@lanl.gov>
Organization: IR
Lines: 22

In article <5073@lanl.gov> jlg@lanl.gov (Jim Giles) writes:
> From article <1622:Nov606:57:0190@kramden.acf.nyu.edu>, by brnstnd@kramden.acf.nyu.edu (Dan Bernstein):
> | In article <3652@lanl.gov> jlg@lanl.gov (Jim Giles) writes:
> |>       x(1,:) = x(2,:)
> |   [ easy to see that there's no aliasing ]
> |   [ C version it's much harder, especially with the rows flipped ]
> | Jim, I sympathize with the point you're trying to make, but this has
> | absolutely nothing to do with pointers. If language L has array slicing
> | and array assignment, then it will understand the above statement
> | directly, and can optimize just as easily as Fortran. Pointers never
> | appear.
> However, the context of this discussion is whether to use arrays or
> to use pointers _instead_.

Exactly. That's why your example has nothing to do with this discussion.
It should convince people that array slicing and array copying are
useful features. I don't think any programmer is going to replace a
single language builtin (such as x(1,:) = x(2,:)) with a series of
statements, unless he's done some extensive tests showing how poorly the
compiler handles the builtin.

---Dan