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From: Alan Mackenzie <acm@muc.de>
To: Stefan Monnier <monnier@iro.umontreal.ca>
Cc: 66750@debbugs.gnu.org, Andrea Corallo <acorallo@gnu.org>,
	Stefan Kangas <stefankangas@gmail.com>,
	acm@muc.de
Subject: bug#66750: Unhelpful text in C-h v for variables with a lambda form as value
Date: Sat, 28 Oct 2023 18:17:04 +0000	[thread overview]
Message-ID: <ZT1QIC9T__WSn87L@ACM> (raw)
In-Reply-To: <jwv5y2qr7v8.fsf-monnier+emacs@gnu.org>

Hello, Stefan.

On Sat, Oct 28, 2023 at 13:17:13 -0400, Stefan Monnier wrote:
> >> > Currently feature/named-lambdas is mostly working, not fully working.

> Didn't know about this feature.

It's been hanging around the savannah repository since July.

> I like the idea of keeping better track of the origin of lambda
> expressions (tho, admittedly, the same problem occurs with other kinds
> of data: I have several times been faced with a keymap or a char-table,
> wondering where the heel it came from).

Maybe something similar might be possible for those type of objects.

> I took a look at

>     git log -p main..origin/feature/named-lambdas

> but that's 127kB, so ... could [you] briefly describe the overall design
> (IOW, how it's seen by ELisp programmers, byte-compiler hackers, and
> ELisp users)?

Certainly.  Each lambda expression has (usually) a defun within which it
is defined.  Sometimes it's in a defvar, or defcustom.  That
@dfn{defining symbol} is recorded in the lambda form in one of three
ways:
(i) For a cons form, it's (cadr form), a new field inserted between the
  symbol `lambda' and the argument list.
(ii) For a byte-compiled form, it's (aref form 5), this new field going
  after the doc string and before any interactive form in the compiled
  form.
(iii) For a native-compiled subr it's (subr-native-defining-symbol
subr), a function defined in data.c.  It accesses a new field in struct
Lisp_Subr called defining_symbol.

There are lots of detailed changes in eval.c and bytecomp.el (and
friends).  Also the macro `lambda' in subr.el has been amended to insert
the current global defining-symbol if there isn't already a non-nil
symbol in that position.  cl-print-object/compiled-function has been
amended to print the defining-symbol, and there is a new
cl-print-object/subr which does the same.

The intention is that compiled objects from earlier Emacsen can still be
loaded and run by feature/named-lambdas, just without the defining
symbols (which will appear to be nil).

> Also, what other approaches have you considered/tried and what were the
> problems you've encountered, if any?

feature/named-lambdas was originally intended for use in backtraces.

For the current bug, I've considered individually replacing each lambda
with a named defun, so that C-h v will show that name rather than an
unhelpful byte/native compiled anonymous function.  That would be a lot
of work - my scripting found 63 defcustoms set to lambdas, 29 uses in
doc strings, and 215 suspicious occurrences with ordinary variables
(quite a few of which will be harmless).  Amending all these (I guess
around 200 lambdas) would probably be too much work.

>         Stefan

-- 
Alan Mackenzie (Nuremberg, Germany).





  reply	other threads:[~2023-10-28 18:17 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-10-25 17:09 bug#66750: Unhelpful text in C-h v for variables with a lambda form as value Alan Mackenzie
2023-10-25 20:53 ` Andrea Corallo
2023-10-27 11:35   ` Alan Mackenzie
2023-10-28  9:27     ` Alan Mackenzie
2023-10-28 15:04     ` Stefan Kangas
2023-10-28 15:59       ` Alan Mackenzie
2023-10-28 16:26         ` Eli Zaretskii
2023-10-28 16:57           ` Alan Mackenzie
2023-10-28 17:17         ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-10-28 18:17           ` Alan Mackenzie [this message]
2023-10-28 18:38             ` Eli Zaretskii
2023-10-28 18:59               ` Alan Mackenzie
2023-10-28 19:13             ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-10-28 19:59               ` Alan Mackenzie
2023-10-29  4:14                 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-10-29 11:25                   ` Alan Mackenzie
2023-10-29 16:32                     ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-10-29 18:50                       ` Alan Mackenzie
2023-10-29 21:47                         ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-10-30  9:44                           ` Alan Mackenzie
2023-11-01 12:47                             ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-11-01 15:03                               ` Alan Mackenzie
2023-11-01 18:11                                 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-11-01 20:30                                   ` Alan Mackenzie
2023-11-01 22:46                                     ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-11-02  6:13                                       ` Eli Zaretskii
2023-11-02  9:37                                         ` Alan Mackenzie
2023-11-02 10:09                                           ` Eli Zaretskii
2023-11-02 11:52                                             ` Alan Mackenzie
2023-11-02 13:50                                               ` Eli Zaretskii
2023-11-02 15:55                                                 ` Alan Mackenzie
2023-11-02 16:50                                                   ` Eli Zaretskii
2023-11-02 17:12                                                     ` Andrea Corallo
2023-11-02 21:44                                                   ` Stefan Kangas
2023-11-02 22:24                                                     ` Alan Mackenzie
2023-11-03  3:20                                                       ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-11-03 19:46                                                         ` Alan Mackenzie
2023-11-03 22:18                                                           ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-11-04 15:31                                                             ` Alan Mackenzie
2023-11-26 12:32                                                             ` Alan Mackenzie
2023-11-27 17:23                                                               ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2024-03-25 12:03                                                         ` Alan Mackenzie
2023-11-02 20:53               ` Stefan Kangas
2023-11-02 21:20                 ` bug#66750: help-split-fundoc (was: bug#66750: Unhelpful text in C-h v for variables with a lambda form as value) Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors

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