From: David Kastrup <dak@gnu.org>
To: guile-user@gnu.org
Subject: Re: GOOPS with variable number of arguments
Date: Sat, 28 Nov 2015 00:30:12 +0100 [thread overview]
Message-ID: <87r3jbxbp7.fsf@fencepost.gnu.org> (raw)
In-Reply-To: alpine.DEB.2.11.1511272226010.5617@wedemob
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Jan Wedekind <jan@wedesoft.de> writes:
> Hi,
> I am trying to implement n-ary operations for different types of objects.
> When specialising "+" for two arguments, it will automatically work on
> more arguments.
>
> (use-modules (oop goops) (srfi srfi-1))
> (define-generic +)
> (define-method (+ (a <string>) (b <string>)) (string-append a b))
> (+ "a" "b" "c")
> ; "abc"
>
> However I have trouble figuring out a method definition for test which
> would result in the same behaviour.
>
> (define (test . args) ...)
> (define-generic test)
> (define-method (test (a <string>) (b <string>)) (string-append a b))
> (test "a" "b" "c")
> ; "abc"
>
> Please let me know if there is a solution.
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(use-modules (oop goops))
(define-generic test)
(define-method (test a b c . rest)
(if (null? rest) (test (test a b) c)
(apply test (test (test a b) c) rest)))
(define-method (test (a <string>) (b <string>)) (string-append a b))
(display (test "a" "b" "c" "d" "e"))
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--
David Kastrup
next prev parent reply other threads:[~2015-11-27 23:30 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-27 22:58 GOOPS with variable number of arguments Jan Wedekind
2015-11-27 23:30 ` David Kastrup [this message]
2015-11-28 22:24 ` Jan Wedekind
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