From: David Kastrup <dak@gnu.org>
To: 17049@debbugs.gnu.org
Subject: bug#17049: Further change ideas.
Date: Sun, 30 Mar 2014 18:36:20 +0200 [thread overview]
Message-ID: <87ppl3mynv.fsf@fencepost.gnu.org> (raw)
In-Reply-To: <1395314582-22733-1-git-send-email-dak@gnu.org>
While it does not appear like this patch proposal is going anywhere for
some reason, there is a further opportunity for change.
One thing is to note that scm_srfi1_append_reverse_x does essentially
the same thing but has a different doc string, the second argument
non-optional and a different implementation that creates nonsense on
some arguments and hangs on others:
scheme@(guile-user)> (use-modules (srfi srfi-1))
scheme@(guile-user)> (append-reverse! (circular-list 1 2) '(3 4))
$2 = (4 3 1 2 . #-1#)
scheme@(guile-user)> (append-reverse! (circular-list 1) (circular-list 2))
[hangs uninterruptibly...]
It can also show somewhat inventive error messages:
scheme@(guile-user)> (append-reverse! '(1 2 3 . 4) 5)
ERROR: In procedure append-reverse!:
ERROR: In procedure append-reverse!: Wrong type argument in position 1 (expecting list): 4
or even
scheme@(guile-user)> (append-reverse! (circular-list 1 2 3) 5)
ERROR: In procedure append-reverse!:
ERROR: In procedure append-reverse!: Wrong type argument in position 1 (expecting list): 5
It is an obvious candidate to rerouting to reverse!. However, there is
another difference apart from append-reverse! not really being all too
robust against errors:
scheme@(guile-user) [2]> (reverse! (circular-list 1 2 3) 5)
ERROR: In procedure reverse!:
ERROR: In procedure reverse!: Wrong type argument in position 1: (1 2 3 . #-2#)
Entering a new prompt. Type `,bt' for a backtrace or `,q' to continue.
Note that with reverse! the "(expecting list)" in the error message is
absent because scm_wrong_type_arg instead of scm_wrong_type_arg_msg is
employed in scm_reverse_x (directly after the patch, indirectly through
SCM_VALIDATE_LIST before the patch).
So if one wants to have identical error behavior, it would likely make
sense to move to the somewhat more specific scm_wrong_type_arg_msg,
possibly even for the whole of SCM_VALIDATE_LIST.
Of course all this is water under the drawbridge if not even the
original patch is going anywhere.
--
David Kastrup
prev parent reply other threads:[~2014-03-30 16:36 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-20 11:23 bug#17049: [PATCH] Make reverse! forego the cost of SCM_VALIDATE_LIST David Kastrup
2014-03-20 11:38 ` bug#17049: PostScriptum: David Kastrup
2014-03-20 14:19 ` bug#17049: [PATCH] Make reverse! forego the cost of SCM_VALIDATE_LIST David Kastrup
2014-03-20 20:50 ` Andy Wingo
2014-03-20 21:27 ` David Kastrup
2014-03-21 4:38 ` Mark H Weaver
2014-03-21 16:56 ` David Kastrup
2014-03-31 19:56 ` Mark H Weaver
2014-04-01 10:26 ` bug#17049: [PATCH v2] " David Kastrup
2014-04-01 10:40 ` David Kastrup
2014-04-01 14:09 ` Mark H Weaver
2014-04-01 14:24 ` bug#17049: [PATCH v3] " David Kastrup
2014-04-01 16:35 ` Mark H Weaver
2014-03-21 17:44 ` bug#17049: [PATCH] " David Kastrup
2014-03-30 16:36 ` David Kastrup [this message]
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