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From: Andy Wingo <wingo@pobox.com>
To: guile-user@gnu.org
Subject: Re: base class parameterisation?
Date: Tue, 12 Jun 2007 22:50:02 +0200	[thread overview]
Message-ID: <1181681403.4168.105.camel@localhost.localdomain> (raw)
In-Reply-To: <JJCUUL$3D0277CD7F6CDAEA46211A5A993CA88A@poste.it>

Hi Marco,

On Sat, 2007-06-09 at 08:18 +0200, Marco Maggi wrote:
>         ---A---
>        |       |
>        v       v
>        A1      A2
> 
>            B
> 
> I wonder if there is a way to parameterise the construction
> of 'B' to let it have 'A1' or 'A2' as base class. I do not
> want to use delegation.

I suspect you will have to make a metaclass and specialize on
allocate-instance. Something like (my GOOPS is rusty):

(define-class A-metaclass (<class>))

(define-method (allocate-instance (class A-metaclass) initargs)
  (if (random-predicate) (allocate-instance A1) (allocate-instance A2)))

(define-class B () #:metaclass A-metaclass ..)

Good luck,

Andy.
-- 
http://wingolog.org/


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  reply	other threads:[~2007-06-12 20:50 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-06-09  6:18 base class parameterisation? Marco Maggi
2007-06-12 20:50 ` Andy Wingo [this message]
  -- strict thread matches above, loose matches on Subject: below --
2007-06-25 13:57 Marco Maggi

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