dired, toggle ls flags? [elisp]

dired, toggle ls flags? [elisp]

[Emanuel Berg]

How can I hit a key, say h, to toggle the -h flag for ls
in dired?

Answer, like this!

But question, is there already a better way to do it?

Or, if you can improve what I wrote?

If there isn't such a way in core Emacs, I think such
a feature should be added to Emacs since it is really handy.

(defun dired-ls-toggle (opt)
  (let ((opt-re (format "\\(^\\|[[:blank:]]\\)%s\\([[:blank:]]\\|\\b\\)" opt)))
    (if (string-match-p opt-re dired-listing-switches)
        (setq dired-listing-switches
          (replace-regexp-in-string opt-re " " dired-listing-switches) )
      (setq dired-listing-switches (format "%s %s" dired-listing-switches opt)))
    (setq dired-listing-switches (string-clean-whitespace dired-listing-switches))
    (dired-sort-other dired-listing-switches) ))

(defun dired-toggle-human ()
  (interactive)
  (dired-ls-toggle "-h") )

(defun dired-toggle-modification-sort ()
  (interactive)
  (dired-ls-toggle "-t") )

-- 
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Re: dired, toggle ls flags? [elisp]

[Emanuel Berg]

> (defun dired-ls-toggle (opt)
>   (let ((opt-re (format "\\(^\\|[[:blank:]]\\)%s\\([[:blank:]]\\|\\b\\)" opt)))
>     (if (string-match-p opt-re dired-listing-switches)
>         (setq dired-listing-switches
>           (replace-regexp-in-string opt-re " " dired-listing-switches) )
>       (setq dired-listing-switches (format "%s %s" dired-listing-switches opt)))
>     (setq dired-listing-switches (string-clean-whitespace dired-listing-switches))
>     (dired-sort-other dired-listing-switches) ))

I realized the lispy way of doing it, one should first make
a list from the string, then add or remove from that list,
then make a new string from the list.

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Re: dired, toggle ls flags? [elisp]

[Michael Heerdegen via Emacs development discussions.]

Emanuel Berg <incal@dataswamp.org> writes:

> How can I hit a key, say h, to toggle the -h flag for ls
> in dired?
>
> Answer, like this!
>
> But question, is there already a better way to do it?

IIUC, the intended way of changing any flags is C-u s.  Is this good
enough?  We don't have a toggle for all flags.


Michael.

Re: dired, toggle ls flags? [elisp]

[Emanuel Berg]

Michael Heerdegen wrote:

>> How can I hit a key, say h, to toggle the -h flag for ls
>> in dired?
>>
>> Answer, like this!
>>
>> But question, is there already a better way to do it?
>
> IIUC, the intended way of changing any flags is C-u s.
> Is this good enough?

It is the general case, which one should always have.
The specific case, which you do often, you want faster than
that, often.

However this is actually a nontrivial thing to do for the
arbitrary specific case, since, well, take a look at my
initial configuration

(setq dired-listing-switches
  "-A -G -h -l -X --group-directories-first --time-style=long-iso -I \"*.meta\" -I \"#*#\" -I \"*.elc\"")

And it can actually get even worse, as those initial options
can be expressed -AGhlX as well!

So to toggle in general some arbitrary option or option
argument, one would have to parse all those cases: short
options with and without arguments, and the same for long
options, and then grouped short options as well.

So it is a lot of work for a small gain, agreed.

> We don't have a toggle for all flags.

We don't have toggle at all, right? But you can set it
explicitely to whatever you want using what is already there,
which should be fast enough.

If one wants to toggle, well, I'll use my poor man's solution
for the time being at least all tho it would be interesting to
do this so it would work for the entire ls(1) option and
argument syntax and also in an elegant lispy way. Because not
only ls use that syntax as you know, but a lot of other GNU
tools - maybe one can convince oneself it
isn't overengineering?

Also, maybe some other part of Emacs maybe has this kind of
GNU CLI parser already?

-- 
underground experts united
https://dataswamp.org/~incal

Re: dired, toggle ls flags? [elisp]

[Yuri Khan]

On Mon, 29 Apr 2024 at 12:48, Emanuel Berg <incal@dataswamp.org> wrote:

> (setq dired-listing-switches
>   "-A -G -h -l -X --group-directories-first --time-style=long-iso -I \"*.meta\" -I \"#*#\" -I \"*.elc\"")
>
> And it can actually get even worse, as those initial options
> can be expressed -AGhlX as well!
>
> So to toggle in general some arbitrary option or option
> argument, one would have to parse all those cases: short
> options with and without arguments, and the same for long
> options, and then grouped short options as well.

If I had this itch (which I don’t) I think I’d approach it from the
“don’t even try to parse” angle.

1. Choose a subset of switches supported by your ‘ls’. (“All of them”
is a valid subset.)
2. Build a ‘transient’ exposing those. Have it fill out some
reasonable data structure where each switch is a separate field.
3. From that structure, build the ‘dired-listing-switches’ string and
refresh the dired buffer.

Re: dired, toggle ls flags? [elisp]

[Emanuel Berg]

Yuri Khan wrote:

>> So to toggle in general some arbitrary option or option
>> argument, one would have to parse all those cases: short
>> options with and without arguments, and the same for long
>> options, and then grouped short options as well.
>
> If I had this itch (which I don’t) I think I’d approach it
> from the “don’t even try to parse” angle.
>
> 1. Choose a subset of switches supported by your ‘ls’. (“All
>    of them” is a valid subset.)
> 2. Build a ‘transient’ exposing those. Have it fill out some
>    reasonable data structure where each switch is
>    a separate field.
> 3. From that structure, build the ‘dired-listing-switches’
>    string and refresh the dired buffer.

Yes, I thought about this idea. It would work, and one can do
that for the local config, if desired, but not really
a solution to be excited about or push anywhere else.

But this parsing already happens everywhere, in C, if not the
tools themself wouldn't work.

Surely it must happen somewhere in Lisp as well already?

Either in Emacs or in some shell/CLI tool written in Lisp that
use the same style. For example some shell/command interpreter
written in Lisp, since it has to parse arbitrary options
and arguments.

C, bash, zsh, Python all have methods to do it, they are
optional but one is often benefited from using them including
for pretty simple possible input. They come with advantages
like automated interactive documentation and also, simple
input tends to grow when one adds new features.

So one should look for something like that in Lisp as well!

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