bug#53362: 29.0.50; [PATCH] Make Completions sorting a user option

[Protesilaos Stavrou <info@protesilaos.com>]

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On 2022-01-19, 15:27 +0200, Eli Zaretskii <eliz@gnu.org> wrote:

>> From: Protesilaos Stavrou <info@protesilaos.com>
>> Cc: 53362@debbugs.gnu.org
>> Date: Wed, 19 Jan 2022 15:17:13 +0200
>> 
>> >> +(defcustom completions-sort 'lexicographic
>> >> +  "Sort candidates in the *Completions* buffer.
>> >> +
>> >> +The value can be nil to disable sorting altogether,
>> >> +`alphabetical' for alphabetical sorting, `lexicographic' for
>> >> +lexicographic sorting
>> >
>> > Here you expect everyone to understand the subtle difference between
>> > these two sorting orders.  I don't think this expectation is
>> > reasonable.
>> 
>> Perhaps it is better to reference string-lessp and string-version-lessp
>> directly?
>
> That'd be a step backward, IMO.
>
>> > Doesn't string-version-lessp do stuff that is only appropriate with
>> > version numbers like 1.2.3beta?
>> 
>> It also helps when the string starts with a number:
>> 
>>     (sort '("1 test" "21 test" "11 test" "2 test") #'string-lessp)
>>     ;; => ("1 test" "11 test" "2 test" "21 test")
>
> Yes, and how does that match the "alphabetical order" description?

In the revised patch (see attached), I follow the example of
completions-group-sort.

-- 
Protesilaos Stavrou
https://protesilaos.com

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From 3e9e0c2310afdcc921cda2a6d431d7fcbe1eb01a Mon Sep 17 00:00:00 2001
Message-Id: <3e9e0c2310afdcc921cda2a6d431d7fcbe1eb01a.1642601249.git.info@protesilaos.com>
From: Protesilaos Stavrou <info@protesilaos.com>
Date: Wed, 19 Jan 2022 14:20:19 +0200
Subject: [PATCH] Make Completions sorting a user option

* etc/NEWS: Document the new user option.
* lisp/minibuffer.el (completions-sort): Add new user option.
(minibuffer-completion-help): Implement it for the Completions buffer.
---
 etc/NEWS           |  6 ++++++
 lisp/minibuffer.el | 16 +++++++++++++++-
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/etc/NEWS b/etc/NEWS
index 47dbfba9c0..8f68336d30 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -418,6 +418,12 @@ When non-nil, the commands 'next-completion' and 'previous-completion'
 automatically wrap around on reaching the beginning or the end of
 the *Completions* buffer.
 
+*** New user option 'completions-sort'.
+Controls the sorting of the completion candidates in the *Completions*
+buffer.  Available styles are no sorting, alphabetical (the default),
+or a custom sort function (e.g. 'string-version-lessp').  The function
+takes and returns a list of completion candidate strings.
+
 ** Isearch and Replace
 
 +++
diff --git a/lisp/minibuffer.el b/lisp/minibuffer.el
index ab760a42d1..7b7e734b72 100644
--- a/lisp/minibuffer.el
+++ b/lisp/minibuffer.el
@@ -1169,6 +1169,18 @@ (defcustom completion-cycle-threshold nil
   :version "24.1"
   :type completion--cycling-threshold-type)
 
+(defcustom completions-sort 'alphabetical
+  "Sort candidates in the *Completions* buffer.
+
+The value can be nil to disable sorting, `alphabetical' for
+alphabetical sorting or a custom sorting function.  The sorting
+function takes and returns a list of completion candidate
+strings."
+  :type '(choice (const :tag "No sorting" nil)
+                 (const :tag "Alphabetical sorting" alphabetical)
+                 function :tag "Custom function")
+  :version "29.1")
+
 (defcustom completions-group nil
   "Enable grouping of completion candidates in the *Completions* buffer.
 See also `completions-group-format' and `completions-group-sort'."
@@ -2264,7 +2276,9 @@ (defun minibuffer-completion-help (&optional start end)
                       ;; same, but not always.
                       (setq completions (if sort-fun
                                             (funcall sort-fun completions)
-                                          (sort completions 'string-lessp)))
+                                          (pcase completions-sort
+                                            ('alphabetical (sort completions #'string-lessp))
+                                            (_ completions))))
 
                       ;; After sorting, group the candidates using the
                       ;; `group-function'.
-- 
2.34.1