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Newsgroups: comp.lang.ada
Path: swrinde!ihnp4.ucsd.edu!newshub.nosc.mil!news!sampson
From: sampson@nosc.mil (Charles H. Sampson)
Subject: Re: "Subtract C, add Ada"
Message-ID: <1995Feb1.164513.23467@nosc.mil>
Sender: news@nosc.mil
Organization: Computer Sciences Corporation
References: <3gl06i$s03@miranda.gmrc.gecm.com>
Date: Wed, 1 Feb 1995 16:45:13 GMT
Date: 1995-02-01T16:45:13+00:00
List-Id: <comp.lang.ada>

In article <3gl06i$s03@miranda.gmrc.gecm.com>,
R.A.L Williams <bill@valiant> wrote:
>In article <1995Jan23.154631.6702@sei.cmu.edu> you(?) wrote:
>:
>: Again, I don't see it.  The Ada code makes it clear that *corresponding*
>: elements of the array Q are being copied into P - though, of course,
>: a real Ada programmer (TM) would have written just P := Q.  The C code
>: doesn't make that clear - you're going to have to ferret out the
>: initialisations of p and q to determine that.  And if you worry about
>: the correctness of the copy - for instance, whether P and Q are the
>: same size - that's surely going to be a lot easier to establish in Ada.
>
>Again, a simplified example to illustrate a principle. The point is that
>the less I have to move my eyes, or flip over pages, when reading/reviewing 
 ^^^ ^^^^ ^ ^^^^ ^^ ^^^^ ^^ ^^^^  ^^ ^^^^ ^^^^ ^^^^^
>code, the more likely I am to understand it and find any bugs. You're
>quite right, P := Q is an event more compact representation and I approve
>(the Bill Williams official statement of approval!).

     The marked phrases are what many of us Ada fans are talking about when
we use the word _readability_.  P := Q unambiguously shows that the value of
Q is being assigned to P.  To repeat you's statement, *p++ = *q++ simply
says that whatever q was pointing to gets copied to whatever p is pointing
to, after which both are modified to point to the "next" thing.  Depending
on the complexity of the code, it can take a tremendous amount of ferreting
about, moving eyes and flipping pages, to discover what p and q are pointing
to.

				    Charlie