From: maa@liacc.up.pt (Mário Amado Alves)
Subject: Re: How to model unknown values in a vector?
Date: 4 Jun 2003 08:56:39 -0700
Date: 2003-06-04T15:56:40+00:00 [thread overview]
Message-ID: <4a4de33a.0306040756.4bac474@posting.google.com> (raw)
In-Reply-To: bbjgh7$acuc1$1@ID-25716.news.dfncis.de
Ah, the joys of special values :-)
type Valid_Value is new Value
range First_Valid_Value .. Last_Valid_Value;
Unknown : Value := Value'Pred (First_Valid_Value); -- say
Or, the OO way
type Value is tagged with null record;
type Valid_Value is new Value with
record
The_Value : ...
end record;
(But then you'll probably have to use pointers, and in that case there
is always null to signal unknown...)
Both are Ada ways, no implementation dependencies.
prev parent reply other threads:[~2003-06-04 15:56 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-05-31 13:43 How to model unknown values in a vector? Harald Schmidt
2003-05-31 22:47 ` FranciKait
2003-06-01 3:17 ` Jeffrey Carter
2003-06-04 1:04 ` Nick Roberts
2003-06-04 15:56 ` Mário Amado Alves [this message]
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