bug#69133: [PATCH] Make key selection method configurable in EPA.

[Eli Zaretskii <eliz@gnu.org>]

> Date: Wed, 14 Feb 2024 22:47:08 +0300
> From:  Aleksandr Vityazev via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> 
> Currently in epa.el it is possible to select keys only through a
> separate buffer, I think adding the option to select via minibuffer
> would be a nice addition. The current behavior is set to default. Any
> comments?

Thanks, some comments below,

> --- a/etc/NEWS
> +++ b/etc/NEWS
> @@ -1352,6 +1352,14 @@ characters, such as ½ (U+00BD VULGAR FRACTION ONE HALF), are also
>  recognized as rational fractions.  They have been since 2004, but it
>  looks like it was never mentioned in the NEWS, or even the manual.
> 
> +** EasyPG
> +
> +---
> +*** New user option 'epa-keys-select-method'

Heading lines in NEWS should end with a period.

> +This allows the user to customize the key selection method, a minibuffer
> +or buffer option is available, which is set by default and was used in
> +all earlier versions.

This sentence is too complex.  Suggest to reword as two sentences:

  This allows the user to customize the key selection method, which
  can be either by using a pop-up buffer or from the minibuffer.  The
  pop-up buffer method is the default, which preserves previous
  behavior.

Also, why did you decide not to document this in the manual?  epa.el
has its own manual, so how about adding this option to it?

> +(defcustom epa-keys-select-method 'buffer
> +  "Method used to select keys.
> +It can have two values: buffer or minibuffer.
> +Can have two values: buffer or minibuffer.  In the first case, the keys
> +can be selected via a pop-up buffer. In the second case, the keys
> +can be selected via a minibuffer and `completing-read-multiple' will be
> +used."

The doc string could also be simplified.  Like this, for example:

    Method used to select keys in `epa-select-keys'.
  If the value is \\='buffer, the default, keys are selected via a
  pop-up buffer.  If the value is \\='minibuffer, keys are selected
  via the minibuffer instead, using `completing-read-multiple'.

This avoids explaining the values twice (first what they are, then
what they do), and also mentions the default value.

Please also make sure comments, doc strings, and commit log messages
leave two spaces between sentences, per our conventions.  You had a
couple of problems with that in the patch, which my suggested
rephrasing fixed, but please keep this in mind in the future.

> +  :type '(choice (const :tag "Read keys from buffer" buffer)
                                 ^^^^^^^^^^^^^^^^^^^^^
This should probably say "...from a pop-up buffer".

>  (defun epa-select-keys (context prompt &optional names secret)
>    "Display a user's keyring and ask him to select keys.
> @@ -459,7 +484,10 @@ epa-select-keys
>  the keys are listed.
>  If SECRET is non-nil, list secret keys instead of public keys."
>    (let ((keys (epg-list-keys context names secret)))
> -    (epa--select-keys prompt keys)))
> +    (pcase epa-keys-select-method
> +      ('buffer (epa--select-keys prompt keys))
> +      ('minibuffer (epa--select-keys-in-minibuffer prompt keys))
> +      (_ (error "Wrong method for key selection is specified")))))

Hmm... are you assuming users know how to input multiple strings from
the minibuffer, in particular what is the value of crm-separator?  the
function epa--select-keys inserts some instructions into the pop-up
buffer, but this new function you propose just shows the prompt and
nothing else.  Should it somehow help the user with the job of typing
the keys at the prompt?

Also, maybe instead of signaling an error for a value that's neither
'buffer' nor 'minibuffer', we should treat such values as 'buffer'?