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From: Jeffrey Carter <spam.jrcarter.not@spam.not.acm.org>
Newsgroups: comp.lang.ada
Subject: Re: S-expression I/O in Ada
Date: Mon, 09 Aug 2010 12:06:52 -0700
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Date: 2010-08-09T12:06:52-07:00
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On 08/09/2010 11:32 AM, Natacha Kerensikova wrote:
>
> In C for such things I usually use a struct bitfield. I guess the Ada
> equivalent would be a record of Booleans, with a pragma or something
> to have them packed together. Would there be anything wrong with that?
> It seems to me more readable than the above IFs, though from what I
> understood from the rest of the thread it would make CASE on multiple
> bit difficult, and it won't allow slicing (which I'm not sure is a bad
> thing, readability-wise). Is there anything else?

Typically, I would address it using:

type Mode_ID is (Alarm, ...);

type Mode_Set is array (Mode_ID) of Boolean;
for Mode_Set'Component_Size use 1;

Mode : Mode_Set;

if Mode (Alarm) then ...

Of course, I'd usually leave off the 'Component_Size definition; memory is 
usually cheap and plentiful these days. Only if I had to match an existing 
bit-packed representation, or Mode_ID was very large [array (Integer) of 
Boolean, anyone?] would I worry about the representation.

-- 
Jeff Carter
"Run away! Run away!"
Monty Python and the Holy Grail
58

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