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From: "Anders Wirzenius" <anders.wirzenius@pp.qnet.fi>
Newsgroups: comp.lang.ada
References: <97pfmt$ll30@tech.port.ac.uk>
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 <V4%q6.26$OG2.2999@read2.inet.fi> <98idi9$66g$1@hobbes2.crc.com>
Subject: Re: Types, subtypes and ranges
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Date: Tue, 13 Mar 2001 06:40:00 GMT
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Date: 2001-03-13T06:40:00+00:00
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David C. Hoos, Sr. wrote in message <98idi9$66g$1@hobbes2.crc.com>...
>Because TTT'Image is inherited from its base type T.
>
>If you had declared TT and TTT as new T types, the constraint
>error would have occurred, but then you wouldn't have been
>able to add anders to banders without type conversion, because
>the types would have been distinct.

Thanks

I deleted my former code but include my further studies on the subject. It
showed me that the 'Image attribute is inherited all the way up as long as
you don't break the chain of subtypes:

with Ada.Text_IO;
procedure Why_Not_Constraint_Error is
   type T is new Integer;
   subtype TT is T range -2..-1;
   subtype TTT is T range -1..+1;
   subtype TTTT is TTT range -1..0;
   subtype TTTTT is TTTT range 0..0;
   anders : TT := -2;
   bnders : TTTT := 0;
   use Ada.Text_IO;
begin
   Put ( TTTTT'Image ( anders+bnders ) );
end Why_Not_Constraint_Error;

Anders