bug#57212: 29.0.50; [PATCH] Citizen's arrest of end-of-defun-moves-to-eol

bug#57212: 29.0.50; [PATCH] Citizen's arrest of end-of-defun-moves-to-eol

[dick.r.chiang]

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It's a bizarre policy to allow users to inject their personal hooks
willy-nilly.

To the extent I can incur further ill-will, I'll remind the maintainers
feature-flag proliferation is a programming tradition you should
work against, not encourage.  If you're convinced narrowing within
a critical section of redisplay is safe (and I suspect it is), do
it all the time, not just when "long_line_optimizations_p" is true.

Man up, is what I'm saying.  I wish I had your user base to vet my
larger changes.


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From 574fdca333678ccf67c6f403eff6ea27197af272 Mon Sep 17 00:00:00 2001
From: dickmao <dick.r.chiang@gmail.com>
Date: Sun, 14 Aug 2022 13:47:10 -0400
Subject: [PATCH] Squashed commit of the following:

commit e4e6e9b16bca6754ad1d3b176e065fccd72dca98
Author: dickmao <dick.r.chiang@gmail.com>
Date:   Sun Aug 14 13:46:36 2022 -0400

    Revert "Add variable end-of-defun-moves-to-eol"

    This reverts commit 50730a8b04ede381c958600a1400efe8d04d9dfc.

commit fa36e511b9f348e8f3b2555b010c00516c6602aa
Author: dickmao <dick.r.chiang@gmail.com>
Date:   Sun Aug 14 13:46:25 2022 -0400

    Revert "; * lisp/emacs-lisp/lisp.el (end-of-defun-moves-to-eol): Doc fix."

    This reverts commit 564571f712fcf0ffcb93eeca67f7716263c9def5.
(end-of-defun):
---
 lisp/emacs-lisp/lisp.el | 9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

diff --git a/lisp/emacs-lisp/lisp.el b/lisp/emacs-lisp/lisp.el
index acae1a0b0a9..4b85414943a 100644
--- a/lisp/emacs-lisp/lisp.el
+++ b/lisp/emacs-lisp/lisp.el
@@ -507,11 +507,6 @@ end-of-defun-function
 So the function can assume that point is at the beginning of the defun body.
 It should move point to the first position after the defun.")
 
-(defvar end-of-defun-moves-to-eol t
-  "Whether `end-of-defun' moves to eol before doing anything else.
-Set this to nil if this movement adversely affects the buffer's
-major mode's decisions about context.")
-
 (defun buffer-end (arg)
   "Return the \"far end\" position of the buffer, in direction ARG.
 If ARG is positive, that's the end of the buffer.
@@ -543,9 +538,7 @@ end-of-defun
         (push-mark))
     (if (or (null arg) (= arg 0)) (setq arg 1))
     (let ((pos (point))
-          (beg (progn (when end-of-defun-moves-to-eol
-                        (end-of-line 1))
-                      (beginning-of-defun-raw 1) (point)))
+          (beg (progn (end-of-line 1) (beginning-of-defun-raw 1) (point)))
 	  (skip (lambda ()
 		  ;; When comparing point against pos, we want to consider that
 		  ;; if point was right after the end of the function, it's
-- 
2.36.1


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bug#57212: 29.0.50; [PATCH] Citizen's arrest of end-of-defun-moves-to-eol

[Eli Zaretskii]

> From: dick.r.chiang@gmail.com
> Date: Sun, 14 Aug 2022 14:02:55 -0400
> 
> To the extent I can incur further ill-will, I'll remind the maintainers
> feature-flag proliferation is a programming tradition you should
> work against, not encourage.  If you're convinced narrowing within
> a critical section of redisplay is safe (and I suspect it is), do
> it all the time, not just when "long_line_optimizations_p" is true.

If you'd read the code guarded by that flag and understand what it
does, you wouldn't have made such nonsensical proposals.  Safety has
nothing to do with that flag, nothing at all.  The reason is even
spelled out in the documentation and in some comments to the code, if
the code itself is too obscure to grasp.

(And what does this have to do with end-of-defun-moves-to-eol,
anyway??)

bug#57212: 29.0.50; [PATCH] Citizen's arrest of end-of-defun-moves-to-eol

[dick]

> (And what does this have to do with end-of-defun-moves-to-eol,
> anyway??)

I consider end-of-defun-moves-to-eol and long_line_optimizations_p
two additional states that multiply the number of possible
outcomes by 4.  And obfuscatory.

Just answering your question.  It's not clear why you asked since
my responses have always been gibberish to you.

bug#57212: 29.0.50; [PATCH] Citizen's arrest of end-of-defun-moves-to-eol

[Lars Ingebrigtsen]

dick.r.chiang@gmail.com writes:

> -(defvar end-of-defun-moves-to-eol t
> -  "Whether `end-of-defun' moves to eol before doing anything else.
> -Set this to nil if this movement adversely affects the buffer's
> -major mode's decisions about context.")

I'm not much in favour of this variable either, but it fixes a real
problem (that end-of-defun is basically misdesigned -- we move point
before end-of-defun-function, which is just way too DWIM and doesn't
allow you to make end-of-defun-function behave).

A complete redesign would have been better, but I think we're not going
to do that, so I'm closing this bug report.

bug#57212: 29.0.50; [PATCH] Citizen's arrest of end-of-defun-moves-to-eol

[Gregory Heytings]

>
> If you're convinced narrowing within a critical section of redisplay is 
> safe (and I suspect it is), do it all the time, not just when 
> "long_line_optimizations_p" is true.
>

That might indeed be what Emacs could do in the long term, once we have 
enough experience with it.  But it is way too soon to do that now.  FYI, 
you can already do it unconditionally by setting long-line-threshold to 0.

bug#57212: 29.0.50; [PATCH] Citizen's arrest of end-of-defun-moves-to-eol

[Eli Zaretskii]

> Cc: 57212@debbugs.gnu.org
> Date: Mon, 15 Aug 2022 19:44:32 +0000
> From: Gregory Heytings <gregory@heytings.org>
> 
> > If you're convinced narrowing within a critical section of redisplay is 
> > safe (and I suspect it is), do it all the time, not just when 
> > "long_line_optimizations_p" is true.
> 
> That might indeed be what Emacs could do in the long term, once we have 
> enough experience with it.

No, it shouldn't, because of the adverse effects of that on some
aspects of the Emacs behavior.

bug#57212: 29.0.50; [PATCH] Citizen's arrest of end-of-defun-moves-to-eol

[Gregory Heytings]

>>> If you're convinced narrowing within a critical section of redisplay 
>>> is safe (and I suspect it is), do it all the time, not just when 
>>> "long_line_optimizations_p" is true.
>>
>> That might indeed be what Emacs could do in the long term, once we have 
>> enough experience with it.
>
> No, it shouldn't, because of the adverse effects of that on some aspects 
> of the Emacs behavior.
>

Indeed.  I should have added something like "if we find a way to cope with 
these adverse effects".

bug#57212: 29.0.50; [PATCH] Citizen's arrest of end-of-defun-moves-to-eol

[Eli Zaretskii]

> Date: Tue, 16 Aug 2022 08:14:46 +0000
> From: Gregory Heytings <gregory@heytings.org>
> cc: dick.r.chiang@gmail.com, 57212@debbugs.gnu.org
> 
> >>> If you're convinced narrowing within a critical section of redisplay 
> >>> is safe (and I suspect it is), do it all the time, not just when 
> >>> "long_line_optimizations_p" is true.
> >>
> >> That might indeed be what Emacs could do in the long term, once we have 
> >> enough experience with it.
> >
> > No, it shouldn't, because of the adverse effects of that on some aspects 
> > of the Emacs behavior.
> 
> Indeed.  I should have added something like "if we find a way to cope with 
> these adverse effects".

I agree, but I have hard time imagining that miracle, not without
completely redesigning the display engine (and maybe some other parts
of Emacs, like buffer text) based on very different principles.  Most
of the "optimizations" we made are actually shortcuts which ignore
certain aspects of display that we decided were less important than
reasonable response time.