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From: Robert A Duff <bobduff@shell01.TheWorld.com>
Newsgroups: comp.lang.ada
Subject: Re: Seeking for papers about tagged types vs access to subprograms
Date: Mon, 13 May 2013 09:15:34 -0400
Organization: The World Public Access UNIX, Brookline, MA
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Date: 2013-05-13T09:15:34-04:00
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"Yannick Duchêne (Hibou57)" <yannick_duchene@yahoo.fr> writes:

> As said Niklas, the initial idea was requirements on the state of
> objects  for some operation to occur or not occur.

Yes, I understood that.  I just don't think "open/closed file" is
the best example.  Maybe something like, you can't do the "land
aircraft" operation unless you're in the "landing gear down" state.

By the way, Text_IO has more design flaws than I can count without
taking off my shoes.  ;-)

- Bob