Re: Problem with let/cl-letf binding stuff with org-capture

[Bruno Barbier <brubar.cs@gmail.com>]

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Hi Arthur,

Arthur Miller <arthur.miller@live.com> writes:

> Bruno Barbier <brubar.cs@gmail.com> writes:
>
> ...  but I feel a
> bit of passive aggressivity here, for no good reason tbh.

I'm just trying to help, giving some valid or invalid advices.  I'm
sorry that what I wrote, and how I wrote it, made you feel that way.

>>
>> Yes, let binding is fundamental. But I think it's the first time I see
>> 'cl-letf' with the 'symbol-function' place.
>
> https://nullprogram.com/blog/2017/10/27/
> https://endlessparentheses.com/understanding-letf-and-how-it-replaces-flet.html
> https://stackoverflow.com/questions/39550578/in-emacs-what-is-the-difference-between-cl-flet-and-cl-letf
>

Thanks for these links. I like cl-flet and cl-labels :-)


>>> but I am not sure if I can do anything here without introducing at-least an
>>> extra keymap, to not install into the org-capture-mode-map, so I can as well
>>> create a minor mode, but at this point it is not much different than
>>> re-invinting the read-string, so I'll terminate my experiment here :).
>>
>> You can replace the buffer keymap with a keymap that only contain your custom
>> keys, and inherits everything else from org-capture-mode-map.
>
> Isn't that what I wrote: introducing an extra keymap?
> Of course I can solve the problem differently, but that was not what question
> was about :).

Right. Even when inheriting from the old keymap, it's still building a
new keymap.  Sorry :-)


> Well, I definitely understand you, and agree that overwriting function for
> everyone and everything is not the best idea, but unfortunately bindings work as
> they do in Emacs. I would prefer to have a local binding, with cl-flet, but this
> does not work in Emacs:
>
> (defun my-read-string (prompt)
>   (let ((delta 20 )
>         (minibuffer-mode-map org-mode-map))
>     (window-resize (minibuffer-window) delta)
>     (cl-flet ((org-ctrl-c-ctrl-c ()
>                 (interactive)
>                 (let ((s (buffer-string)))
>                   (exit-minibuffer) s))
>               (minibuffer-mode () #'org-mode)
>               (minibuffer-complete-and-exit () #'org-return)
>               (org-kill-note-or-show-branches () #'keyboard-escape-quit))
>       (read-string (concat "# Press C-c C-c to continue, C-c C-k to cancel\n# "
>   prompt "\n\n")))))

Yes. cl-flet looks safe to me :-)

>
> Hooks serve a different purpose. Advice can serve same purpose with exactly
> same side effect, and some other limitations. With some care, let-binding is
> still more "local" then advice. With other words, I agree with you about the
> problems, but not with dogmatic approach that it should never be done, and
> that hooks and advices are the replacement.

Sorry if my words sounding dogmatic.
Else, I agree too :-)


>>
>>> I am very interested to hear more on the topic, since I would definitely like to
>>> learn more about different techniques.
>>
>> Variables are designed to be overriden (let bounds). Functions are not
>
> I have never heard before that functions are not designed to be overriden. I
> think of them as two slots in a symbol structure; let creates bindings for value
> slot, and flet for function slot. Functions are just objects or data as any
> other value in lisp.
>
>> (as there is only one binding at any given time).
>
> Yes, unfortunately, in Emacs it is so;

ok. We do really agree then :-)


> but I don't think it should be > :).

... oh no ! ;-)


>
> There is an interesting package by Nick Ferrier
>
> https://github.com/nicferrier/emacs-noflet

> but it does not seem to work, at least not for me.

It's almost like a temporary advice ;-)


About your use case, if what you need is asynchronous editing, maybe the
with-editor package will be of interest to you:
    https://github.com/magit/with-editor/blob/main/lisp/with-editor.el
    
It allows sub-processes to call Emacs for editing tasks. It's used by
magit. It's easy enough to reuse. I've attached my attempt at it if
you're interested.

best,

Bruno


[-- Attachment #2: my-edit-async draft --]
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(cl-defun my-edit-async (finish &key mode buffer-name setup cancel)
  "Open a buffer, let the user edit its content.
Return the editing buffer.  Call FINISH in the editing buffer if
the user validates his edit (C-c C-c).  When CANCEL is non-nil,
call CANCEL in the editing buffer if the user cancels his
edit (C-c C-k). When done, delete the buffer and its content.

When MODE is non-nil, use it as the major-mode.  When BUFFER-NAME
is non-nil, use it to generate a new unique name of the editing buffer.
When SETUP is non-nil, call it in the edit buffer to setup the
buffer before starting the edit."
  (unless buffer-name (setq buffer-name "@Async edit"))
  (let ((buf (generate-new-buffer buffer-name)))
    (with-current-buffer buf
      (when mode (funcall mode))
      (when setup
        (funcall setup))
      (with-editor-mode 1)
      (setq with-editor-previous-winconf
            (current-window-configuration))
      (add-hook 'with-editor-pre-finish-hook
                (lambda () 
                  (funcall finish)
                  (set-buffer-modified-p nil))
                nil :local)
      (add-hook 'with-editor-pre-cancel-hook
                (lambda ()
                  (when cancel (funcall cancel))
                  (set-buffer-modified-p nil))
                nil :local)
      (switch-to-buffer buf))
    buf))

(my-edit-async 
 (lambda () (message "My edit:\n%S" (buffer-string)))
 :cancel (lambda () (message "Canceled (discarded: %s)" (buffer-string)))
 :setup (lambda () (insert "initial content") (goto-char (point-min))))




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> regards
> /a