From: Jacques GARRIGUE <garrigue@kurims.kyoto-u.ac.jp>
To: skaller@users.sourceforge.net
Cc: caml-list@inria.fr
Subject: Re: [Caml-list] Re: OCAML Downcasting?
Date: Tue, 21 Sep 2004 18:49:34 +0900 (JST) [thread overview]
Message-ID: <20040921.184934.41232635.garrigue@kurims.kyoto-u.ac.jp> (raw)
In-Reply-To: <1095758974.2580.859.camel@pelican.wigram>
From: skaller <skaller@users.sourceforge.net>
> On Tue, 2004-09-21 at 19:15, Jacques GARRIGUE wrote:
>
> > class ['a] button = object (self)
> > inherit ['a] widget
> > method raw = `Button (self :> 'a button)
> > method press = prerr_endline "pressed"
> > end
>
> > Without the self-cast, you cannot extend any class.
>
> Is that an issue with classes or polymorphic variants?
With classes.
If you omit the coercion, any class inheriting from button would have
the type of the raw method specialized to itself, and as a result it
would be incompatible with button.
...
But strangely enough, some tests show that this is not the case. Even
without the coercion, the type of `Button becomes fixed to 'a button.
Looks like there is a bug in the interaction between classes and
variants. So do not forget the coercion even if it works now
without...
Jacques Garrigue
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next prev parent reply other threads:[~2004-09-21 9:50 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <ci7tcf$qqf$1@wolfberry.srv.cs.cmu.edu>
[not found] ` <ci9ggm$i6p$1@wolfberry.srv.cs.cmu.edu>
2004-09-21 8:03 ` Jacques GARRIGUE
2004-09-21 8:43 ` Damien Pous
2004-09-21 9:15 ` Jacques GARRIGUE
2004-09-21 9:29 ` skaller
2004-09-21 9:49 ` Jacques GARRIGUE [this message]
2004-09-21 9:34 ` Stefano Zacchiroli
2004-09-21 9:56 ` Jacques GARRIGUE
2004-09-21 19:27 ` Michael Vanier
2004-09-21 21:38 ` Brian Hurt
2004-09-21 22:06 ` Michael Vanier
2004-09-21 22:32 ` Brian Hurt
2004-09-22 1:04 ` skaller
2004-09-21 22:20 ` Marcin 'Qrczak' Kowalczyk
2004-09-22 2:26 ` skaller
2004-09-22 6:31 ` Marcin 'Qrczak' Kowalczyk
2004-09-22 9:03 ` sejourne_kevin
2004-09-22 10:29 ` Richard Jones
2004-09-22 18:39 ` Brian Hurt
2004-09-22 10:50 ` skaller
2004-09-22 12:03 ` Alain Frisch
2004-09-22 12:50 ` Cláudio Valente
2004-09-22 13:15 ` Marcin 'Qrczak' Kowalczyk
2004-09-22 15:50 ` skaller
2004-09-22 18:42 ` Brian Hurt
2004-09-22 18:44 ` Marcin 'Qrczak' Kowalczyk
2004-09-22 19:18 ` Brian Hurt
2004-09-22 0:50 ` skaller
2004-09-22 1:30 ` Jacques GARRIGUE
2004-09-22 2:59 ` skaller
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