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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: Efficient Sequential Access to Arrays
Date: Thu, 26 Jul 2012 20:49:34 +0200
Organization: cbb software GmbH
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Date: 2012-07-26T20:49:34+02:00
List-Id: <comp.lang.ada>

On Thu, 26 Jul 2012 13:35:46 -0400, Dennis Lee Bieber wrote:

> 	My prior job had a, uhm, valid use for 'Valid... the code had to
> receive data structures generated externally (and passed through half a
> dozen converters from hardware signal pins to software emulation), along
> with receiving "commands" from test engineers that came from some
> database (converting text string into enumeration values).
> 
> 	A mismatch between the software build and the database could result
> in an (currently) invalid representation/enumeration value being passed
> in.

I know this case well because getting data out/into hardware is my daily
job. I do not consider it legitimate for 'Valid. To put it clearer, I don't
see re-interpretation of some bit pattern a good design. Which is what
actually happens before 'Valid. It is always worth 10ns or so CPU time of
doing proper conversion or value construction per arithmetic operations
instead. It is not only cleaner, it is also safer, because 'Valid is a very
illusory protection against mangled input.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de