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From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: Re: AI12-0218:  What is the portable representation clause for
 processing IETF packets on little-endian machines?
Date: Wed, 30 May 2018 07:39:07 +0100
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Date: 2018-05-30T07:39:07+01:00
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"Randy Brukardt" <randy@rrsoftware.com> writes:

> "Simon Wright" <simon@pushface.org> wrote in message 
> news:ly4litj7qx.fsf@pushface.org...

>> But it doesn't do byte swapping.
>
> Thank goodness. People use rep. clauses all the time in code that
> permeates an entire program; having very expensive byte swapping code
> easily triggered would give Ada a reputation of being a slug (rather
> than understanding that the code misuses the features). The whole idea
> of portable representation clauses is close to misuse of the feature
> (the entire value is to ensure that compilers for the same target
> intepret the clauses the same way).

(a) In that case, the LRM should point out this potential problem in red
block caps; or eliminate rep clauses altogether and make us use C-style
shifts and masks (I think that's what Dmitry does anyway).

(b) My experience of rep clauses is communication with other machines,
be they NTP time servers over a network or hardware interface cards. I
don't understand "ensure that compilers for the same target intepret the
clauses the same way".