From: Rob Browning <rlb@defaultvalue.org>
To: 37461@debbugs.gnu.org
Cc: control@debbugs.gnu.org
Subject: bug#37461: define-generic doesn't promote equal? to generic
Date: Sat, 21 Sep 2019 10:15:41 -0500 [thread overview]
Message-ID: <87lfuh3cki.fsf@trouble.defaultvalue.org> (raw)
In-Reply-To: <87blvfzx1f.fsf@trouble.defaultvalue.org>
retitle 37461 Methods added to primitive generics don't always work
thanks
Rob Browning <rlb@defaultvalue.org> writes:
> A re-export doesn't affect the module using the re-exporter, and export
> and replace both fail with "Unbound variable: equal?", even though
> there's a (define equal? ...) in the module.
It looks like equal? isn't changed by define-generic, etc. because it
already has "generic-capability?". And in fact, I can see that defining
a method on it does alter its primitive-generic-generic, but then
dispatch to the new method doesn't always seem to work (or perhaps I
just misunderstand the dispatch rules).
Here a one argument specialization doesn't work, but a two argument
specialization does -- for new classes, but not for a "standard" class
like <string>:
scheme@(guile-user)> (use-modules (oop goops))
scheme@(guile-user)> (primitive-generic-generic equal?)
$1 = #<<generic> equal? (1)>
scheme@(guile-user)> (define-class <foo> () (data))
scheme@(guile-user)> (define-method (equal? (x <foo>)) 'x)
scheme@(guile-user)> (primitive-generic-generic equal?)
$2 = #<<generic> equal? (2)>
scheme@(guile-user)> (equal? (make <foo>))
$3 = #t
scheme@(guile-user)> (define-method (equal? (x <foo>) (y <foo>)) 'x)
$4 = #<<generic> equal? (3)>
scheme@(guile-user)> (equal? (make <foo>) (make <foo>))
$5 = x
scheme@(guile-user)> (define-method (equal? (x <string>) (y <string>)) 'x)
$6 = #<<generic> equal? (4)>
scheme@(guile-user)> (equal? "x" "y")
$7 = #f
Thanks
--
Rob Browning
rlb @defaultvalue.org and @debian.org
GPG as of 2011-07-10 E6A9 DA3C C9FD 1FF8 C676 D2C4 C0F0 39E9 ED1B 597A
GPG as of 2002-11-03 14DD 432F AE39 534D B592 F9A0 25C8 D377 8C7E 73A4
next prev parent reply other threads:[~2019-09-21 15:15 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-19 15:37 bug#37461: define-generic doesn't promote equal? to generic Rob Browning
2019-09-19 23:27 ` Rob Browning
2019-09-21 15:15 ` Rob Browning [this message]
2019-09-21 17:08 ` Rob Browning
2019-09-23 15:01 ` Mikael Djurfeldt
2019-09-28 16:51 ` Mikael Djurfeldt
2019-09-28 17:31 ` Rob Browning
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