From: Maciej Sobczak <no.spam@no.spam.com>
Subject: Re: subtype of enumeration type
Date: Mon, 20 Mar 2006 16:18:34 +0100
Date: 2006-03-20T16:18:34+01:00 [thread overview]
Message-ID: <dvmh49$3v7$1@sunnews.cern.ch> (raw)
In-Reply-To: <gmiRaAP4tbKY@eisner.encompasserve.org>
Larry Kilgallen wrote:
> type Day is (Mon, Tue, Thu, Fri, Wed, Sat, Sun);
> subtype Weekday is Day range Mon .. Wed;
> subtype Schoolday is Day range Mon .. Fri;
First of all, I might need to define the subtypes *after* Day is defined
and I might not have write access to the module where Day is defined.
Second, let's say that in addition I get the piano lessons all Tuesdays,
Wednesdays and Thursdays:
subtype Pianoday is Day <what goes here?>;
> Some additional logic may also be in order if you print some
> some human-readable output based on an iteration
This additional logic would be needed only because you have changed the
order of elements in the primary type for the purpose of defining the
subtype, thus introducing the *reverse* source code dependency between
these types.
In other words, the need for this "additional logic" is exactly the
indication that this solution is not acceptable.
So - is it at all possible? If yes, how? If not, what is the sense of
providing these kind of examples even in RM, if the concept simply does
not work?
--
Maciej Sobczak : http://www.msobczak.com/
Programming : http://www.msobczak.com/prog/
next prev parent reply other threads:[~2006-03-20 15:18 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-03-20 13:31 subtype of enumeration type Maciej Sobczak
2006-03-20 14:26 ` Larry Kilgallen
2006-03-20 15:18 ` Maciej Sobczak [this message]
2006-03-20 15:37 ` Robert A Duff
2006-03-20 20:29 ` Björn Persson
2006-03-20 21:41 ` Jeffrey R. Carter
2006-03-21 8:37 ` subtypes and preconditions (was: subtype of enumeration type) Peter Amey
2006-03-21 17:42 ` subtypes and preconditions Jeffrey R. Carter
2006-03-21 19:00 ` Georg Bauhaus
2006-03-22 1:54 ` Jeffrey R. Carter
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