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From: mheaney@ni.net (Matthew Heaney)
Subject: Re: Rules for Representation of Subtypes
Date: 1996/09/29
Message-ID: <mheaney-ya023180002909961041210001@news.ni.net>#1/1
X-Deja-AN: 186070411
references: <dewar.843920464@schonberg> <DyGy7y.Hy5@world.std.com>
content-type: text/plain; charset=ISO-8859-1
organization: Estormza Software
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newsgroups: comp.lang.ada
Date: 1996-09-29T00:00:00+00:00
List-Id: <comp.lang.ada>


In article <DyGy7y.Hy5@world.std.com>, bobduff@world.std.com (Robert A
Duff) wrote:

>In article <dewar.843920464@schonberg>,
>Robert Dewar <dewar@schonberg.cs.nyu.edu> wrote:
>I wrote:
>>It should."
>And Robert replied:
>>I am completely puzzled, you can specify the size of types and the size of
>>objects, what on earth woul it mean to specify Storage_Size for an array
>>(as opposed to specifying the type or object size for the array).
>
>The complaint was that Ada measures everythng in bits, and why can't you
>specify sizes in bytes, or storage units, or whatever, which is much
>more convenient in many cases.  That's what I was saying "It should" to.

And I agree, too!

   O'Storage_Units

makes a lot more sense than

   O'Size / System.Storage_Unit

Why not just save me the trouble, and make 'Storage_Units a predefined
language attribute?

I'd actually go further and make

   O'Bytes 

a predefined language attribute, which the compiler is free to reject if
Storage_Unit /= 8 on this machine.

I'm always a little nervous when I'm making an OS call that explicitly
calls for length in bytes, yet I have to express the length in terms of
Storage_Units.  I know that thinking in terms Storage_Units is more
portable, but there's nothing portable about 

   Starlet.QIO (
      ...
      P1 => O'Address,
      P2 => O'Size / System.Storage_Unit,
      ...

QIO  wants bytes, so why not let me say that directly?

>- Bob

matt

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Matthew Heaney
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(818) 985-1271