From: Eli Zaretskii <eliz@gnu.org>
To: Sebastian Miele <iota@whxvd.name>,
Stefan Monnier <monnier@iro.umontreal.ca>
Cc: 64835@debbugs.gnu.org
Subject: bug#64835: ‘describe-variable’ unconditionally let-binds ‘print-circle’ to t
Date: Mon, 24 Jul 2023 20:03:39 +0300 [thread overview]
Message-ID: <83o7k1qm1g.fsf@gnu.org> (raw)
In-Reply-To: <87zg3lmf1v.fsf@whxvd.name> (message from Sebastian Miele on Mon, 24 Jul 2023 18:42:09 +0200)
> From: Sebastian Miele <iota@whxvd.name>
> Date: Mon, 24 Jul 2023 18:42:09 +0200
>
> That was not the case in Emacs 28. It seems to have been introduced
> in the following commit:
>
> 2c18969c810f338d73beda592ee5af7103132e97
> Author: Stefan Monnier <monnier@iro.umontreal.ca>
> AuthorDate: Thu Mar 2 02:08:08 2017 -0500
> Commit: Stefan Monnier <monnier@iro.umontreal.ca>
> CommitDate: Thu Mar 2 02:08:32 2017 -0500
>
> * lisp/help-fns.el (describe-variable): Use cl-print for the value
>
> Use `pp-buffer' rather than `pp' so as to avoid calling prin1 twice.
>
> 2017 is a while ago. The first pretest release of Emacs 28 was in
> December 2021. So the commit must have entered the current emacs-29
> branch in some "non-linear" way.
I don't think so. I see this code in Emacs 28.1. So I'm not sure why
you didn't see this behavior in Emacs 28, if indeed it is caused by
print-circle.
> The problem is that the effect of ‘print-circle’ being t pertains to
> all sharing, not just sharing that leads to circles. And that has the
> effect, that the output can become arbitrarily unreadable. Consider
> for example:
>
> (require 'ispell)
> (ispell-set-spellchecker-params)
> (describe-variable 'ispell-dictionary-alist)
>
> The display of the value in my machine contains, e.g., "(nil #1# #2# #3#
> t #4# nil utf-8)".
>
> I do not see the reason for hard-coding ‘print-circle’ to t in
> ‘describe-variable’. The only reason I can imagine would be the
> prevention of infinite loops. But that cannot be the case, because
> even with ‘print-circle’ nil, the printing routines seem to check for
> circularity and handle it gracefully in the output.
>
> Is this a bug or a necessity that I do not understand, yet?
>
> The NEWS file does not mention this change.
>
> In general (and somewhat unrelated), it would be nice if ‘print-circle’
> would be split into two things: (1) make explicit all sharing (as is
> done now), and (2) make explicit only a subset of sharing that resolves
> all circles. (The latter would in at least two aspects still be
> different from the graceful handling mentioned above when ‘print-circle’
> is nil.)
Adding Stefan to the discussion.
next prev parent reply other threads:[~2023-07-24 17:03 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-24 16:42 bug#64835: ‘describe-variable’ unconditionally let-binds ‘print-circle’ to t Sebastian Miele
2023-07-24 17:03 ` Eli Zaretskii [this message]
2023-07-24 17:23 ` Sebastian Miele
2023-08-06 2:54 ` Michael Heerdegen
2023-08-08 3:00 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-08-08 3:55 ` Michael Heerdegen
2023-08-08 12:55 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-08-06 10:09 ` Mattias Engdegård
2023-08-15 2:55 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-08-15 12:24 ` Mattias Engdegård
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