GNU bug report logs - #10723
24.0.93; bad pp formatting for `C-h v' with list value

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: "Drew Adams" <drew.adams <at> oracle.com>
To: <bug-gnu-emacs <at> gnu.org>
Subject: 24.0.93; bad pp formatting for `C-h v' with list value
Date: Sat, 4 Feb 2012 09:39:39 -0800

This is a REGRESSION which starts with Emacs 23 (no problem before 23).
 
emacs -Q
 
(setq foobar '(some-symbol ((some . cons) "some-string")))
 
C-h v foobar
 
Shows:
 
foobar's value is (some-symbol
 ((some . cons)
  "some-string"))
 
Please do not start the pretty-printed value on the same line as
"foobar's value is" if the pretty-printed value EITHER:
 
a. uses more than one line (i.e. contains newline chars)
 
OR
 
b. is longer than the standard *Help* output line length (`fill-column')
MINUS the length of "foobar's value is " (where "foobar" is replaced by
the variable's name)
 

In GNU Emacs 24.0.93.1 (i386-mingw-nt5.1.2600)
 of 2012-01-29 on MARVIN
Windowing system distributor `Microsoft Corp.', version 5.1.2600
Configured using:
 `configure --with-gcc (4.6) --no-opt --cflags
 -ID:/devel/emacs/libs/libXpm-3.5.8/include
 -ID:/devel/emacs/libs/libXpm-3.5.8/src
 -ID:/devel/emacs/libs/libpng-dev_1.4.3-1/include
 -ID:/devel/emacs/libs/zlib-dev_1.2.5-2/include
 -ID:/devel/emacs/libs/giflib-4.1.4-1/include
 -ID:/devel/emacs/libs/jpeg-6b-4/include
 -ID:/devel/emacs/libs/tiff-3.8.2-1/include
 -ID:/devel/emacs/libs/gnutls-3.0.9/include --ldflags
 -LD:/devel/emacs/libs/gnutls-3.0.9/lib'
 

Message #8 received at 10723 <at> debbugs.gnu.org (full text, mbox):

From: "Drew Adams" <drew.adams <at> oracle.com>
To: <10723 <at> debbugs.gnu.org>
Subject: RE: bug#10723: 24.0.93; bad pp formatting for `C-h v' with list value
Date: Sun, 16 Sep 2012 17:17:13 -0700

ping

regression

Message #11 received at 10723 <at> debbugs.gnu.org (full text, mbox):

From: Lars Ingebrigtsen <larsi <at> gnus.org>
To: "Drew Adams" <drew.adams <at> oracle.com>
Cc: 10723 <at> debbugs.gnu.org
Subject: Re: bug#10723: 24.0.93; bad pp formatting for `C-h v' with list value
Date: Sat, 08 Feb 2014 21:16:46 -0800

"Drew Adams" <drew.adams <at> oracle.com> writes:

> This is a REGRESSION which starts with Emacs 23 (no problem before 23).
>
> emacs -Q
>
> (setq foobar '(some-symbol ((some . cons) "some-string")))
>
> C-h v foobar
>
> Shows:
>
> foobar's value is (some-symbol
>  ((some . cons)
>   "some-string"))
>
> Please do not start the pretty-printed value on the same line as
> "foobar's value is" if the pretty-printed value EITHER:
>
> a. uses more than one line (i.e. contains newline chars)
>
> OR
>
> b. is longer than the standard *Help* output line length (`fill-column')
> MINUS the length of "foobar's value is " (where "foobar" is replaced by
> the variable's name)

I can confirm that this still exists in Emacs 24.3.

-- 
(domestic pets only, the antidote for overdose, milk.)
  bloggy blog http://lars.ingebrigtsen.no/

Message #18 received at 10723 <at> debbugs.gnu.org (full text, mbox):

From: Lars Ingebrigtsen <larsi <at> gnus.org>
To: "Drew Adams" <drew.adams <at> oracle.com>
Cc: 10723 <at> debbugs.gnu.org
Subject: Re: bug#10723: 24.0.93; bad pp formatting for `C-h v' with list value
Date: Thu, 28 Apr 2016 15:13:22 +0200

Man, the logic in that function is weird.

Here's some of the outputs:

lala’s value is
(ooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo)

Fine.

lala’s value is (ooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo
 (oo))

Er.

lala’s value is (oo (oo))

Fine, I guess...

lala’s value is (zot
 (bar)
 (foo)
 (zot)
 (fooooooooooooooo0000000000))

Which was your original complaint.

----
lala’s value is shown below.

Documentation:
Not documented as a variable.

Value: (zot
 (bar)
 (foo)
 (zot)
 (bar)
 (foo)
 (zot)
 (bar)
 (foo)
 (zot)
 (bar)
 (foo)
 (zot)
 (fooooooooooooooo0000000000))
----

So when it's very long it moves to a totally different format with a
"below" clause.

The uncommented "logic" here is this, mostly: 

		  (if (< (+ (length print-rep) (point) (- line-beg)) 68)
		      (insert print-rep)
		    (terpri)
		    (pp val)
		    (if (< (point) (+ 68 (line-beginning-position 0)))
			(delete-region from (1+ from))
		      (delete-region (1- from) from)))

Which means "if the final line of the pp'd expression is shorter than 68
characters, then delete the newline after 'value ', otherwise delete the
trailing space".

I think that's a slight thinko.  I'm changing it to "if the pp'd
expression is more than one line, then etc".

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

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