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From: tmoran@acm.org
Newsgroups: comp.lang.ada
Subject: Re: Address and bit mask
Date: Mon, 29 Aug 2011 18:46:28 +0000 (UTC)
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Date: 2011-08-29T18:46:28+00:00
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> As far as I understand, your solution is to convert the address in
> address_integer, manipulating it, and then converting it in address.
> And all that stuff is because Address type is defined as private.
> Am I right ?
>
> > Size/range of addresses are rather target dependent, so I'm curious as
> > to what you wish to make 'portable'?...
>
> I mean a solution that works with the Address type without the need to
> redefine everything.

  "New_Paint_Color := Old_Paint_Color + 3;" makes no sense in general,
though in certain circumstances adding 3 to the numeric representation of
a color may make a great deal of sense.  Similarly, ANDing two addresses
does not in general make any sense, but sometimes ANDing their bitwise
representation may be just the thing.  Ada tries to operate at the level
of abstraction where a color is a color, not a number, and an address is
an address, not a number.  The compiler will catch abstraction level
mismatches.  If you want to do something at a lower abstraction level, you
have to tell the compiler you are changing levels.  That's what
System.Storage_Elements is for.