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Re: GOOPS constructors

From: Marko Rauhamaa
Subject: Re: GOOPS constructors
Date: Tue, 22 Jul 2014 16:03:43 +0300
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/23.3 (gnu/linux)

Tobias Brandt <address@hidden>:

> Couldn't just define <square> like this:
> (define-class <square> (<rectangle>))
> then define a side method:
> (define-method (side (@ <square>)) (slot-ref @ 'height))
> This way, you're not storing the same information twice.

Well, I was trying to find a simple toy example to demonstrate the need,
but maybe I'll need to find a more compelling one.

How about:

(define-class <error> ()
  (msg #:getter msg #:init-keyword #:msg))

(define-class <file-error> (<error>)
  (path #:getter path #:init-keyword #:path)
  (code #:getter code #:init-keyword #:code)
  (fs #:getter fs #:init-keyword #:fs))

(define-method (initialize (@ <file-error>) args)
   args #f ((path #f) (code #f) (fs #f))
   (next-method @ (list #:msg (format #f "File error in ~S (~S)" path code)))))

How do I now write the getters for path, code and fs?


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