From: "Peter C. Chapin" <pchapin@sover.net>
Subject: Re: Subtype conformance... not what I was expecting.
Date: Wed, 26 Jul 2006 20:02:53 -0400
Date: 2006-07-26T20:02:53-04:00 [thread overview]
Message-ID: <44c802a7$0$2922$4d3efbfe@news.sover.net> (raw)
In-Reply-To: <1153928329.4980.14.camel@localhost>
Georg Bauhaus wrote:
> Let F : Person -> Room and G : Girl -> Girls_Dormitory.
> Then Person -> Room is a subtype of Girl -> Girls_Dormitory (that is,
> Person->Room <: Girl->Girls_Dormitory) iff Room <: Girls_Dormitory
> and Girl <: Person.
>
> Let F : Girl -> Girls_Dormitory and G : Person -> Room.
> Then Girl -> Girls_Dormitory is a subtype of Person -> Room (that is,
> Girl->Girls_Dormitory <: Person->Room) iff Girls_Dormitory <: Room
> and Person <: Girl.
Yes, this is what I was getting at: covariance and contravariance. I
think what you say above is correct. However, it is not intuitive for
Room <: Girls_Dormitory or for Person <: Girl.
Peter
next prev parent reply other threads:[~2006-07-27 0:02 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-07-26 3:02 Subtype conformance... not what I was expecting Peter C. Chapin
2006-07-26 6:58 ` Craig Carey
2006-07-26 7:54 ` Dmitry A. Kazakov
2006-07-26 14:32 ` Peter C. Chapin
2006-07-26 15:38 ` Georg Bauhaus
2006-07-27 0:02 ` Peter C. Chapin [this message]
2006-07-26 18:40 ` Dmitry A. Kazakov
2006-07-27 0:00 ` Peter C. Chapin
2006-07-26 8:06 ` Georg Bauhaus
2006-07-26 14:15 ` Peter C. Chapin
2006-07-26 21:23 ` Adam Beneschan
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