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From: mheaney@ni.net (Matthew Heaney)
Subject: Re: Packed array size question....
Date: 1997/03/16
Message-ID: <mheaney-ya023680001603971621360001@news.ni.net>#1/1
X-Deja-AN: 226050747
References: <01bc2b36$b64477a0$f5093e9f@lsm8-pc.linkabit.titan.com>
 <dewar.857784634@merv> <mheaney-ya023680001303970016240001@news.ni.net>
 <01bc300c$247f6200$0e096dce@my-pc.neosoft.com>
Organization: Estormza Software
Newsgroups: comp.lang.ada
Date: 1997-03-16T00:00:00+00:00
List-Id: <comp.lang.ada>


In article <01bc300c$247f6200$0e096dce@my-pc.neosoft.com>, "Pat Rogers"
<progers@acm.org> wrote:

>> You have to admit that the attribute
>> 
>> X'Size_In_Storage_Elements 
>> 
>> would make a lot of sense.  In practice, knowing the number of storage
>> elements occupied by an object is much more useful than knowing the
>number
>> of bits.
>> 
>> Surprisingly, this attribute was not included in Ada 95!
>
>>From the RM:
>
>145     S�Max_Size_In_Storage_Elements
>        For every subtype S:
>
>146     Denotes the maximum value for Size_In_Storage_Elements that will be
>requested via Allocate for an
>        access type whose designated subtype is S. The value of this
attribute is
>of type universal_integer. 
>        See 13.11.1.
>
>Close enough?

No, because that attribute only applies to memory allocated via an allocator.  

I wanted an attribute I could apply to stack objects:

declare
   O : T;
begin
   write (addr => O'Address, nbytes => O'Size_In_Storage_Elements);
end;

instead of

declare
   O : T;
begin
   write (addr => O'Address, nbytes => O'Size / 8);
end;

(Of course, T is a first-named subtype whose size is an integral multiple
of System.Storage_Unit.  And in this case, System.Storage_Unit = 8.)

Matt

--------------------------------------------------------------------
Matthew Heaney
Software Development Consultant
<mailto:matthew_heaney@acm.org>
(818) 985-1271