GNU bug report logs - #66224
[PATCH] Add optional PREDICATE argument to read-directory-name

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

From: Joseph Turner <joseph <at> breatheoutbreathe.in>
To: Emacs Bugs Mailing List <bug-gnu-emacs <at> gnu.org>
Subject: [PATCH] Add optional PREDICATE argument to read-directory-name
Date: Tue, 26 Sep 2023 18:16:40 -0700

[Message part 1 (text/plain, inline)]

Hello!

This patch makes read-directory-name accept an optional PREDICATE arg
so it can be used like read-file-name.

Joseph

[0001-Add-optional-PREDICATE-argument-to-read-directory-na.patch (text/x-diff, attachment)]

Message #8 received at 66224 <at> debbugs.gnu.org (full text, mbox):

From: Philip Kaludercic <philipk <at> posteo.net>
To: Joseph Turner <joseph <at> breatheoutbreathe.in>
Cc: 66224 <at> debbugs.gnu.org
Subject: Re: bug#66224: [PATCH] Add optional PREDICATE argument to
 read-directory-name
Date: Thu, 28 Sep 2023 09:05:03 +0000

Joseph Turner <joseph <at> breatheoutbreathe.in> writes:

> Hello!
>
> This patch makes read-directory-name accept an optional PREDICATE arg
> so it can be used like read-file-name.
>
> Joseph
>
>>From 78ba02683bd163d8991b182ec4e8ec370e734f95 Mon Sep 17 00:00:00 2001
> From: Joseph Turner <joseph <at> breatheoutbreathe.in>
> Date: Tue, 26 Sep 2023 18:14:23 -0700
> Subject: [PATCH] Add optional PREDICATE argument to read-directory-name
>
> * lisp/files.el (read-directory-name): Add optional PREDICATE arg.
> * doc/lispref/minibuf.texi (Reading File Names): Document change.
> * etc/NEWS: Note change.
> ---
>  doc/lispref/minibuf.texi | 6 ++++--
>  etc/NEWS                 | 4 ++++
>  lisp/files.el            | 8 +++++---
>  3 files changed, 13 insertions(+), 5 deletions(-)
>
> diff --git a/doc/lispref/minibuf.texi b/doc/lispref/minibuf.texi
> index 620c58ec6e9..c3528ea74d2 100644
> --- a/doc/lispref/minibuf.texi
> +++ b/doc/lispref/minibuf.texi
> @@ -1709,7 +1709,7 @@ If this variable is non-@code{nil}, @code{read-file-name} ignores case
>  when performing completion.
>  @end defopt
>  
> -@defun read-directory-name prompt &optional directory default require-match initial
> +@defun read-directory-name prompt &optional directory default require-match initial predicate
>  This function is like @code{read-file-name} but allows only directory
>  names as completion alternatives.
>  
> @@ -1719,7 +1719,9 @@ combining @var{directory} (or the current buffer's default directory
>  if @var{directory} is @code{nil}) and @var{initial}.  If both
>  @var{default} and @var{initial} are @code{nil}, this function uses
>  @var{directory} as substitute default, or the current buffer's default
> -directory if @var{directory} is @code{nil}.
> +directory if @var{directory} is @code{nil}.  The union of sixth arg
> +@code{predicate} and @code{file-directory-p} is passed as the
> +@code{predicate} argument to ‘read-file-name’.
>  @end defun
>  
>  @defopt insert-default-directory
> diff --git a/etc/NEWS b/etc/NEWS
> index 1b3532b5657..ee0143b1958 100644
> --- a/etc/NEWS
> +++ b/etc/NEWS
> @@ -3541,6 +3541,10 @@ This function is called to see whether what the user has typed is a
>  match.  This is also available from functions that call
>  'completing-read', like 'read-file-name'.
>  
> +** 'read-directory-name' now accepts an optional PREDICATE argument.
> +The union of sixth arg PREDICATE and 'file-directory-p' is passed
> +as the PREDICATE argument to 'read-file-name'.
> +
>  ** 'posn-col-row' can now give position data based on windows.
>  Previously, it reported data only based on the frame.
>  
> diff --git a/lisp/files.el b/lisp/files.el
> index b72f141c0ee..e78e8ea0a36 100644
> --- a/lisp/files.el
> +++ b/lisp/files.el
> @@ -807,7 +807,7 @@ See Info node `(elisp)Standard File Names' for more details."
>      (dos-convert-standard-filename filename))
>     (t filename)))
>  
> -(defun read-directory-name (prompt &optional dir default-dirname mustmatch initial)
> +(defun read-directory-name (prompt &optional dir default-dirname mustmatch initial predicate)
>    "Read directory name, prompting with PROMPT and completing in directory DIR.
>  Value is not expanded---you must call `expand-file-name' yourself.
>  Default name to DEFAULT-DIRNAME if user exits with the same
> @@ -821,14 +821,16 @@ Fourth arg MUSTMATCH non-nil means require existing directory's name.
>   Non-nil and non-t means also require confirmation after completion.
>  Fifth arg INITIAL specifies text to start with.
>  DIR should be an absolute directory name.  It defaults to
> -the value of `default-directory'."
> +the value of `default-directory'.
> +The union of sixth arg PREDICATE and `file-directory-p' is passed
> +as the PREDICATE argument to `read-file-name'."
>    (unless dir
>      (setq dir default-directory))
>    (read-file-name prompt dir (or default-dirname
>  				 (if initial (expand-file-name initial dir)
>  				   dir))
>  		  mustmatch initial
> -		  'file-directory-p))
> +		  (and #'file-directory-p predicate)))

I am not sure this makes sense, #'file-directory-p is always non-nil but
a PREDICATE will only be passed on to `read-file-name' is PREDICATE is
also non-nil.  So if no PREDICATE is passed, the expression ignored
#'file-directory-p, breaking `read-directory-name', or am I mistaken (I
haven't tried it out)?

>  
>  
>  (defun pwd (&optional insert)

Message #11 received at 66224 <at> debbugs.gnu.org (full text, mbox):

From: Joseph Turner <joseph <at> breatheoutbreathe.in>
To: Philip Kaludercic <philipk <at> posteo.net>
Cc: 66224 <at> debbugs.gnu.org
Subject: Re: bug#66224: [PATCH] Add optional PREDICATE argument to
 read-directory-name
Date: Thu, 28 Sep 2023 20:28:52 -0700

[Message part 1 (text/plain, inline)]

Philip Kaludercic <philipk <at> posteo.net> writes:
>
> I am not sure this makes sense, #'file-directory-p is always non-nil but
> a PREDICATE will only be passed on to `read-file-name' is PREDICATE is
> also non-nil.  So if no PREDICATE is passed, the expression ignored
> #'file-directory-p, breaking `read-directory-name', or am I mistaken (I
> haven't tried it out)?

Oops! Thanks for catching my error!! The attached patch should actually
do what I intended.

Joseph

[0001-Add-optional-PREDICATE-argument-to-read-directory-na.patch (text/x-diff, attachment)]

Message #14 received at 66224 <at> debbugs.gnu.org (full text, mbox):

From: Joseph Turner <joseph <at> breatheoutbreathe.in>
To: Philip Kaludercic <philipk <at> posteo.net>
Cc: 66224 <at> debbugs.gnu.org
Subject: Re: bug#66224: [PATCH] Add optional PREDICATE argument to
 read-directory-name
Date: Thu, 28 Sep 2023 20:28:52 -0700

[Message part 1 (text/plain, inline)]

Philip Kaludercic <philipk <at> posteo.net> writes:
>
> I am not sure this makes sense, #'file-directory-p is always non-nil but
> a PREDICATE will only be passed on to `read-file-name' is PREDICATE is
> also non-nil.  So if no PREDICATE is passed, the expression ignored
> #'file-directory-p, breaking `read-directory-name', or am I mistaken (I
> haven't tried it out)?

Oops! Thanks for catching my error!! The attached patch should actually
do what I intended.

Joseph

[0001-Add-optional-PREDICATE-argument-to-read-directory-na.patch (text/x-diff, attachment)]

Message #17 received at 66224 <at> debbugs.gnu.org (full text, mbox):

From: Michael Heerdegen <michael_heerdegen <at> web.de>
To: Joseph Turner via "Bug reports for GNU Emacs, the Swiss army knife of
 text editors" <bug-gnu-emacs <at> gnu.org>
Cc: Philip Kaludercic <philipk <at> posteo.net>, 66224 <at> debbugs.gnu.org,
 Joseph Turner <joseph <at> breatheoutbreathe.in>
Subject: Re: bug#66224: [PATCH] Add optional PREDICATE argument to
 read-directory-name
Date: Fri, 29 Sep 2023 05:54:31 +0200

Joseph Turner via "Bug reports for GNU Emacs, the Swiss army knife of
text editors" <bug-gnu-emacs <at> gnu.org> writes:

> -		  'file-directory-p))
> +                  (lambda (filename)
> +                    (if predicate
> +                        (and (file-directory-p filename)
> +                             (funcall predicate filename))
> +                      (file-directory-p filename)))))

Yip.  Nitpick: The code will be faster if you move the test out of the
predicate (so that it will not be performed repeatedly):

#+begin_src emacs-lisp
(if predicate
    (lambda (filename)
      (and (file-directory-p filename)
           (funcall predicate filename)))
  #'file-directory-p)
#+end_src


Michael.

Message #23 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Joseph Turner <joseph <at> breatheoutbreathe.in>
To: Michael Heerdegen <michael_heerdegen <at> web.de>
Cc: "Joseph Turner via Bug reports for GNU Emacs, the Swiss army knife of
 text editors" <bug-gnu-emacs <at> gnu.org>, 66224 <at> debbugs.gnu.org,
 Philip Kaludercic <philipk <at> posteo.net>
Subject: Re: bug#66224: [PATCH] Add optional PREDICATE argument to
 read-directory-name
Date: Thu, 28 Sep 2023 21:19:24 -0700

[Message part 1 (text/plain, inline)]

Michael Heerdegen <michael_heerdegen <at> web.de> writes:

> Joseph Turner via "Bug reports for GNU Emacs, the Swiss army knife of
> text editors" <bug-gnu-emacs <at> gnu.org> writes:
>
>> -		  'file-directory-p))
>> +                  (lambda (filename)
>> +                    (if predicate
>> +                        (and (file-directory-p filename)
>> +                             (funcall predicate filename))
>> +                      (file-directory-p filename)))))
>
> Yip.  Nitpick: The code will be faster if you move the test out of the
> predicate (so that it will not be performed repeatedly):
>
> #+begin_src emacs-lisp
> (if predicate
>     (lambda (filename)
>       (and (file-directory-p filename)
>            (funcall predicate filename)))
>   #'file-directory-p)
> #+end_src

Thank you!! See attached patch.

Joseph

[0001-Add-optional-PREDICATE-argument-to-read-directory-na.patch (text/x-diff, attachment)]

Message #29 received at 66224 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Joseph Turner <joseph <at> breatheoutbreathe.in>
Cc: 66224 <at> debbugs.gnu.org
Subject: Re: bug#66224: [PATCH] Add optional PREDICATE argument to
 read-directory-name
Date: Fri, 29 Sep 2023 15:05:44 +0300

> Date: Tue, 26 Sep 2023 18:16:40 -0700
> From:  Joseph Turner via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <bug-gnu-emacs <at> gnu.org>
> 
> This patch makes read-directory-name accept an optional PREDICATE arg
> so it can be used like read-file-name.

Any rationale?

> @@ -1719,7 +1719,9 @@ combining @var{directory} (or the current buffer's default directory
>  if @var{directory} is @code{nil}) and @var{initial}.  If both
>  @var{default} and @var{initial} are @code{nil}, this function uses
>  @var{directory} as substitute default, or the current buffer's default
> -directory if @var{directory} is @code{nil}.
> +directory if @var{directory} is @code{nil}.  The union of sixth arg
> +@code{predicate} and @code{file-directory-p} is passed as the

This should be elaborated: what is meant by "the union of sixth arg
and 'file-directory-p'"?

> +@code{predicate} argument to ‘read-file-name’.
                                ^^^^^^^^^^^^^^^^
That should be @code{read-file-name}

> +** 'read-directory-name' now accepts an optional PREDICATE argument.
> +The union of sixth arg PREDICATE and 'file-directory-p' is passed
> +as the PREDICATE argument to 'read-file-name'.

Likewise here, regarding the "union" part.

Also, since you submit the patch for the manual, this NEWS entry
should be marked with "+++".

>  Fifth arg INITIAL specifies text to start with.
>  DIR should be an absolute directory name.  It defaults to
> -the value of `default-directory'."
> +the value of `default-directory'.
> +The union of sixth arg PREDICATE and `file-directory-p' is passed
> +as the PREDICATE argument to `read-file-name'."

The "union" part again.

Thanks.

Message #32 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Michael Heerdegen <michael_heerdegen <at> web.de>
To: Joseph Turner via "Bug reports for GNU Emacs, the Swiss army knife of
 text editors" <bug-gnu-emacs <at> gnu.org>
Cc: philipk <at> posteo.net, 66224 <at> debbugs.gnu.org,
 Joseph Turner <joseph <at> breatheoutbreathe.in>
Subject: Re: bug#66224: [PATCH] Add optional PREDICATE argument to
 read-directory-name
Date: Tue, 03 Oct 2023 05:30:32 +0200

Joseph Turner via "Bug reports for GNU Emacs, the Swiss army knife of
text editors" <bug-gnu-emacs <at> gnu.org> writes:

> Thank you!! See attached patch.

Yes, thanks, the code LGTM now.

You know that the predicate will be ignored when MUSTMATCH is t?
The behavior is not different than for `read-file-name'.

I think your patch is definitely a step in the right direction, but I
also still think we should think about the semantics of the restricting
arguments as a whole.

Michael.

Message #38 received at 66224 <at> debbugs.gnu.org (full text, mbox):

From: Joseph Turner <joseph <at> breatheoutbreathe.in>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: 66224 <at> debbugs.gnu.org
Subject: Re: bug#66224: [PATCH] Add optional PREDICATE argument to
 read-directory-name
Date: Tue, 03 Oct 2023 16:08:57 -0700

[Message part 1 (text/plain, inline)]

Eli Zaretskii <eliz <at> gnu.org> writes:

>> Date: Tue, 26 Sep 2023 18:16:40 -0700
>> From:  Joseph Turner via "Bug reports for GNU Emacs,
>>  the Swiss army knife of text editors" <bug-gnu-emacs <at> gnu.org>
>>
>> This patch makes read-directory-name accept an optional PREDICATE arg
>> so it can be used like read-file-name.
>
> Any rationale?

Mainly code clarity. If you want to prompt for a certain type of
directory, then IMO the intent is more clear like this:

(read-directory-name "Prompt: " "~/" nil nil nil #'my/predicate)

than like this:

(read-file-name "Prompt: " "~/" nil nil nil
                (lambda (filename)
                  (and (funcall #'file-directory-p filename)
                       (funcall #'my/predicate filename))))

Also, I think that it would follow the principle of least suprise to
have read-file-name and read-directory-name accept the same args.

>> @@ -1719,7 +1719,9 @@ combining @var{directory} (or the current buffer's default directory
>>  if @var{directory} is @code{nil}) and @var{initial}.  If both
>>  @var{default} and @var{initial} are @code{nil}, this function uses
>>  @var{directory} as substitute default, or the current buffer's default
>> -directory if @var{directory} is @code{nil}.
>> +directory if @var{directory} is @code{nil}.  The union of sixth arg
>> +@code{predicate} and @code{file-directory-p} is passed as the
>
> This should be elaborated: what is meant by "the union of sixth arg
> and 'file-directory-p'"?
>
>> +@code{predicate} argument to ‘read-file-name’.
>                                 ^^^^^^^^^^^^^^^^
> That should be @code{read-file-name}
>
>> +** 'read-directory-name' now accepts an optional PREDICATE argument.
>> +The union of sixth arg PREDICATE and 'file-directory-p' is passed
>> +as the PREDICATE argument to 'read-file-name'.
>
> Likewise here, regarding the "union" part.
>
> Also, since you submit the patch for the manual, this NEWS entry
> should be marked with "+++".
>
>>  Fifth arg INITIAL specifies text to start with.
>>  DIR should be an absolute directory name.  It defaults to
>> -the value of `default-directory'."
>> +the value of `default-directory'.
>> +The union of sixth arg PREDICATE and `file-directory-p' is passed
>> +as the PREDICATE argument to `read-file-name'."
>
> The "union" part again.

Thanks for the review!! Please see attached patch.

Best,

Joseph

[0001-Add-optional-PREDICATE-argument-to-read-directory-na.patch (text/x-diff, attachment)]

Message #41 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Joseph Turner <joseph <at> breatheoutbreathe.in>
To: Michael Heerdegen <michael_heerdegen <at> web.de>
Cc: "Joseph Turner via Bug reports for GNU Emacs, the Swiss army knife of
 text editors" <bug-gnu-emacs <at> gnu.org>, 66224 <at> debbugs.gnu.org,
 philipk <at> posteo.net
Subject: Re: bug#66224: [PATCH] Add optional PREDICATE argument to
 read-directory-name
Date: Tue, 03 Oct 2023 16:20:27 -0700

Michael Heerdegen <michael_heerdegen <at> web.de> writes:

> You know that the predicate will be ignored when MUSTMATCH is t?
> The behavior is not different than for `read-file-name'.

I'm not sure what you mean. In both of the following examples, PREDICATE
is used to narrow the completion candidates to only empty directories:

(read-directory-name "Prompt: " "~/" nil t nil #'directory-empty-p)
(read-directory-name "Prompt: " "~/" nil nil nil #'directory-empty-p)

Thank you!

Joseph

Message #47 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Michael Heerdegen <michael_heerdegen <at> web.de>
To: Joseph Turner via "Bug reports for GNU Emacs, the Swiss army knife of
 text editors" <bug-gnu-emacs <at> gnu.org>
Cc: philipk <at> posteo.net, 66224 <at> debbugs.gnu.org,
 Joseph Turner <joseph <at> breatheoutbreathe.in>
Subject: Re: bug#66224: [PATCH] Add optional PREDICATE argument to
 read-directory-name
Date: Thu, 05 Oct 2023 03:23:50 +0200

Joseph Turner via "Bug reports for GNU Emacs, the Swiss army knife of
text editors" <bug-gnu-emacs <at> gnu.org> writes:

> I'm not sure what you mean. In both of the following examples, PREDICATE
> is used to narrow the completion candidates to only empty directories:
>
> (read-directory-name "Prompt: " "~/" nil t nil #'directory-empty-p)
> (read-directory-name "Prompt: " "~/" nil nil nil #'directory-empty-p)

In the second version also non-empty directories will be accepted.

Michael.

Message #53 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Joseph Turner <joseph <at> breatheoutbreathe.in>
To: Michael Heerdegen <michael_heerdegen <at> web.de>
Cc: "Joseph Turner via Bug reports for GNU Emacs, the Swiss army knife of
 text editors" <bug-gnu-emacs <at> gnu.org>, 66224 <at> debbugs.gnu.org,
 philipk <at> posteo.net
Subject: Re: bug#66224: [PATCH] Add optional PREDICATE argument to
 read-directory-name
Date: Wed, 04 Oct 2023 18:34:30 -0700

Michael Heerdegen <michael_heerdegen <at> web.de> writes:

> Joseph Turner via "Bug reports for GNU Emacs, the Swiss army knife of
> text editors" <bug-gnu-emacs <at> gnu.org> writes:
>
>> I'm not sure what you mean. In both of the following examples, PREDICATE
>> is used to narrow the completion candidates to only empty directories:
>>
>> (read-directory-name "Prompt: " "~/" nil t nil #'directory-empty-p)
>> (read-directory-name "Prompt: " "~/" nil nil nil #'directory-empty-p)
>
> In the second version also non-empty directories will be accepted.

Yes, PREDICATE narrows the completion candidates but doesn't determine a
valid return value.

Message #59 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Joseph Turner <joseph <at> breatheoutbreathe.in>
To: Michael Heerdegen <michael_heerdegen <at> web.de>, "Joseph Turner via Bug
 reports for GNU Emacs, the Swiss army knife of   text editors"
 <bug-gnu-emacs <at> gnu.org>, 66224 <at> debbugs.gnu.org, philipk <at> posteo.net
Subject: Re: bug#66224: [PATCH] Add optional PREDICATE argument to
 read-directory-name
Date: Sun, 12 Nov 2023 12:42:42 -0800

Joseph Turner <joseph <at> breatheoutbreathe.in> writes:

> Michael Heerdegen <michael_heerdegen <at> web.de> writes:
>
>> Joseph Turner via "Bug reports for GNU Emacs, the Swiss army knife of
>> text editors" <bug-gnu-emacs <at> gnu.org> writes:
>>
>>> I'm not sure what you mean. In both of the following examples, PREDICATE
>>> is used to narrow the completion candidates to only empty directories:
>>>
>>> (read-directory-name "Prompt: " "~/" nil t nil #'directory-empty-p)
>>> (read-directory-name "Prompt: " "~/" nil nil nil #'directory-empty-p)
>>
>> In the second version also non-empty directories will be accepted.
>
> Yes, PREDICATE narrows the completion candidates but doesn't determine a
> valid return value.

Ping!  I'm happy to keep discussing this patch if others are interested.

Message #65 received at 66224 <at> debbugs.gnu.org (full text, mbox):

From: Stefan Kangas <stefankangas <at> gmail.com>
To: Joseph Turner <joseph <at> breatheoutbreathe.in>
Cc: michael_heerdegen <at> web.de, philipk <at> posteo.net, 66224 <at> debbugs.gnu.org
Subject: Re: bug#66224: [PATCH] Add optional PREDICATE argument to
 read-directory-name
Date: Sat, 13 Jan 2024 04:53:52 -0600

Joseph Turner <joseph <at> breatheoutbreathe.in> writes:

> Joseph Turner <joseph <at> breatheoutbreathe.in> writes:
>
>> Michael Heerdegen <michael_heerdegen <at> web.de> writes:
>>
>>> Joseph Turner via "Bug reports for GNU Emacs, the Swiss army knife of
>>> text editors" <bug-gnu-emacs <at> gnu.org> writes:
>>>
>>>> I'm not sure what you mean. In both of the following examples, PREDICATE
>>>> is used to narrow the completion candidates to only empty directories:
>>>>
>>>> (read-directory-name "Prompt: " "~/" nil t nil #'directory-empty-p)
>>>> (read-directory-name "Prompt: " "~/" nil nil nil #'directory-empty-p)
>>>
>>> In the second version also non-empty directories will be accepted.
>>
>> Yes, PREDICATE narrows the completion candidates but doesn't determine a
>> valid return value.
>
> Ping!  I'm happy to keep discussing this patch if others are interested.

Could you please send the latest version of your patch?

Message #70 received at 66224 <at> debbugs.gnu.org (full text, mbox):

From: Joseph Turner <joseph <at> breatheoutbreathe.in>
To: Stefan Kangas <stefankangas <at> gmail.com>
Cc: michael_heerdegen <at> web.de, philipk <at> posteo.net, 66224 <at> debbugs.gnu.org
Subject: Re: bug#66224: [PATCH] Add optional PREDICATE argument to
 read-directory-name
Date: Sat, 13 Jan 2024 11:26:25 -0800

[Message part 1 (text/plain, inline)]

Stefan Kangas <stefankangas <at> gmail.com> writes:

> Joseph Turner <joseph <at> breatheoutbreathe.in> writes:
>
>> Joseph Turner <joseph <at> breatheoutbreathe.in> writes:
>>
>>> Michael Heerdegen <michael_heerdegen <at> web.de> writes:
>>>
>>>> Joseph Turner via "Bug reports for GNU Emacs, the Swiss army knife of
>>>> text editors" <bug-gnu-emacs <at> gnu.org> writes:
>>>>
>>>>> I'm not sure what you mean. In both of the following examples, PREDICATE
>>>>> is used to narrow the completion candidates to only empty directories:
>>>>>
>>>>> (read-directory-name "Prompt: " "~/" nil t nil #'directory-empty-p)
>>>>> (read-directory-name "Prompt: " "~/" nil nil nil #'directory-empty-p)
>>>>
>>>> In the second version also non-empty directories will be accepted.
>>>
>>> Yes, PREDICATE narrows the completion candidates but doesn't determine a
>>> valid return value.
>>
>> Ping!  I'm happy to keep discussing this patch if others are interested.
>
> Could you please send the latest version of your patch?

Here you go!

[0001-Add-optional-PREDICATE-argument-to-read-directory-na.patch (text/x-diff, inline)]

From 894e44bce60cf30c9e8bc8c5323eaed91d135bbb Mon Sep 17 00:00:00 2001
From: Joseph Turner <joseph <at> breatheoutbreathe.in>
Date: Thu, 28 Sep 2023 20:27:47 -0700
Subject: [PATCH] Add optional PREDICATE argument to read-directory-name

* lisp/files.el (read-directory-name): Add optional PREDICATE arg.
* doc/lispref/minibuf.texi (Reading File Names): Document change.
* etc/NEWS: Note change.
---
 doc/lispref/minibuf.texi |  7 +++++--
 etc/NEWS                 |  5 +++++
 lisp/files.el            | 13 ++++++++++---
 3 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/doc/lispref/minibuf.texi b/doc/lispref/minibuf.texi
index 620c58ec6e9..bf4d6e13d3a 100644
--- a/doc/lispref/minibuf.texi
+++ b/doc/lispref/minibuf.texi
@@ -1709,7 +1709,7 @@ If this variable is non-@code{nil}, @code{read-file-name} ignores case
 when performing completion.
 @end defopt
 
-@defun read-directory-name prompt &optional directory default require-match initial
+@defun read-directory-name prompt &optional directory default require-match initial predicate
 This function is like @code{read-file-name} but allows only directory
 names as completion alternatives.
 
@@ -1719,7 +1719,10 @@ combining @var{directory} (or the current buffer's default directory
 if @var{directory} is @code{nil}) and @var{initial}.  If both
 @var{default} and @var{initial} are @code{nil}, this function uses
 @var{directory} as substitute default, or the current buffer's default
-directory if @var{directory} is @code{nil}.
+directory if @var{directory} is @code{nil}.  When optional sixth
+argument @code{predicate} is non-nil, the union of @code{predicate}
+and @code{file-directory-p} is passed as the @code{predicate} argument
+to @code{read-file-name}.
 @end defun
 
 @defopt insert-default-directory
diff --git a/etc/NEWS b/etc/NEWS
index 1b3532b5657..fb9f6a0b43f 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -3541,6 +3541,11 @@ This function is called to see whether what the user has typed is a
 match.  This is also available from functions that call
 'completing-read', like 'read-file-name'.
 
+** 'read-directory-name' now accepts an optional PREDICATE argument.
+When optional sixth argument PREDICATE is non-nil, the union of
+PREDICATE and 'file-directory-p' is passed as the PREDICATE argument
+to 'read-file-name'.
+
 ** 'posn-col-row' can now give position data based on windows.
 Previously, it reported data only based on the frame.
 
diff --git a/lisp/files.el b/lisp/files.el
index b72f141c0ee..68855cd1c6d 100644
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -807,7 +807,7 @@ See Info node `(elisp)Standard File Names' for more details."
     (dos-convert-standard-filename filename))
    (t filename)))
 
-(defun read-directory-name (prompt &optional dir default-dirname mustmatch initial)
+(defun read-directory-name (prompt &optional dir default-dirname mustmatch initial predicate)
   "Read directory name, prompting with PROMPT and completing in directory DIR.
 Value is not expanded---you must call `expand-file-name' yourself.
 Default name to DEFAULT-DIRNAME if user exits with the same
@@ -821,14 +821,21 @@ Fourth arg MUSTMATCH non-nil means require existing directory's name.
  Non-nil and non-t means also require confirmation after completion.
 Fifth arg INITIAL specifies text to start with.
 DIR should be an absolute directory name.  It defaults to
-the value of `default-directory'."
+the value of `default-directory'.
+When sixth arg PREDICATE is non-nil, the union of PREDICATE and
+`file-directory-p' is passed as the PREDICATE argument to
+`read-file-name'. Otherwise, only `file-directory-p' is passed."
   (unless dir
     (setq dir default-directory))
   (read-file-name prompt dir (or default-dirname
 				 (if initial (expand-file-name initial dir)
 				   dir))
 		  mustmatch initial
-		  'file-directory-p))
+                  (if predicate
+                      (lambda (filename)
+                        (and (file-directory-p filename)
+                             (funcall predicate filename)))
+                    #'file-directory-p)))
 
 
 (defun pwd (&optional insert)
-- 
2.41.0

Message #75 received at 66224-done <at> debbugs.gnu.org (full text, mbox):

From: Stefan Kangas <stefankangas <at> gmail.com>
To: Joseph Turner <joseph <at> breatheoutbreathe.in>
Cc: michael_heerdegen <at> web.de, philipk <at> posteo.net, 66224-done <at> debbugs.gnu.org
Subject: Re: bug#66224: [PATCH] Add optional PREDICATE argument to
 read-directory-name
Date: Thu, 13 Feb 2025 01:49:29 -0600

Version: 31.1

Joseph Turner <joseph <at> breatheoutbreathe.in> writes:

>> Could you please send the latest version of your patch?
>
> Here you go!

Thanks for the patch!

Installed on master as commit 3f1d84d593b.  Note that I partially
omitted the addition to the manual since we treat other optional
arguments by simply referring back to the read-file-name documentation.

In the followup commit 069c8ff6d58, I also made substantial changes to
the `read-directory-name` docstring.  The majority of that was not
directly related to your changes, however.

I'm consequently closing this bug report.

Message #78 received at 66224 <at> debbugs.gnu.org (full text, mbox):

From: Joseph Turner <joseph <at> breatheoutbreathe.in>
To: help-debbugs <at> gnu.org (GNU bug Tracking System)
Cc: 66224 <at> debbugs.gnu.org
Subject: Re: bug#66224: closed (Re: bug#66224: [PATCH] Add optional
 PREDICATE argument to read-directory-name)
Date: Thu, 13 Feb 2025 13:49:04 -0800

help-debbugs <at> gnu.org (GNU bug Tracking System) writes:

> Your bug report
>
> #66224: [PATCH] Add optional PREDICATE argument to read-directory-name
>
> which was filed against the emacs package, has been closed.
>
> The explanation is attached below, along with your original report.
> If you require more details, please reply to 66224 <at> debbugs.gnu.org.

Thank you, Stefan!

Joseph

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