From: Stefan Monnier <monnier@iro.umontreal.ca>
To: "João Távora" <joaotavora@gmail.com>
Cc: emacs-devel@gnu.org
Subject: Re: scratch/backend-completion c807121fbd 1/2: Add lisp/backend-completion.el
Date: Tue, 29 Nov 2022 16:18:57 -0500 [thread overview]
Message-ID: <jwvv8mxpjrd.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <878rjzuhgv.fsf@gmail.com> ("João Távora"'s message of "Fri, 25 Nov 2022 16:28:00 +0000")
>> Maybe a good way to do that is to provide a (backend-completion-table
>> FUNC CATEGORY &optional METADATA) where FUN is a function which handles
>> the tryc and allc cases (maybe the `tryc` handling could even be
>> optional, depending on how the `tryc` case is usually handled (do
>> backends often provide something usable for `tryc`?)). That function
>> would then return an appropriate completion-table (function), and would
>> make sure along the way that CATEGORY is mapped to `completion-backend`
>> in the `completion-category-defaults`.
>
> I get the idea, I think. I thought about this, but I'm not sure this
> can be made generic enough to service the three examples I know of:
> Eglot, SLY and the eel.el thing I've been using lately.
I can't see why it wouldn't be just as general as what we have now.
(defun backend-completion-table ( tryc-function allc-function
category &optional metadata)
(unless (assq category completion-category-defaults)
(push `(,category (styles completion-backend))
`completion-category-defaults))
(lambda (string pred action)
(pcase action
(`metadata
`(metadata (category . ,category) . ,metadata))
(`(backend-completion-tryc . ,point)
;; FIXME: Obey `pred`? Pass it to `tryc`?
`(backend-completion-tryc . ,(funcall tryc string point)))
(`(backend-completion-allc . ,point)
(let ((all (funcall allc string point)))
`(backend-completion-allc . ,(seq-filter pred all))))
(`(boundaries . ,_) nil)
(t
(let ((all (funcall allc string (length string))))
(complete-with-action action all string pred))))))
>> That `backend-completion-table` would also have the benefit that it
>> could make sure the completion-table it returns also behaves sanely
>> with other styles (i.e. also handle the "normal" completion table
>> requests), whereas otherwise the temptation would be very high for users
>> of this package to use "completion table functions" which only handle
>> the `backend-completion-tryc/allc` requests and fail pathetically when
>> another style is used. Similarly `backend-completion-table` could also
>> make sure PRED is obeyed.
>
> Alright. But please, follow up with some code. You're probably right,
> but this whole thing is too complicated for me to understand.
See above.
>>> (add-to-list 'completion-category-overrides
>>> - '(eglot-indirection-joy (styles . (eglot--lsp-backend-style))))
>>> + '(eglot-indirection-joy (styles . (backend-completion-backend-style))))
Wow! I didn't pay attention at first, but I now see you're modifying
`completion-category-overrides` which is the user-facing variable.
You should modify `completion-category-defaults` instead!
>> Any reason not to call that completion category just `eglot`?
>
> Yes, 'eglot' is already a different completion category, for
> completion-at-point, with a different structure.
> `eglot-indirection-joy' is just a product of my usual confusion with
> this whole jungle of concepts: I just vaguely understand it's an
> indirection so I called it accordingly for mental reference. But feel
> free to suggest a better name.
I'm not very familiar with Eglot's code but based on a cursory check, it
seems this is used specifically when completing an identifier for things
like `xref`, so maybe `eglot-identifier` (and maybe `eglot` should be
renamed to `eglot-code` since it's used to complete the actual code in
the buffer)?
Stefan
next prev parent reply other threads:[~2022-11-29 21:18 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <166938157708.15020.14294469350904271113@vcs2.savannah.gnu.org>
[not found] ` <20221125130621.A3C14C0E4C1@vcs2.savannah.gnu.org>
2022-11-25 15:50 ` scratch/backend-completion c807121fbd 1/2: Add lisp/backend-completion.el Stefan Monnier
2022-11-25 16:28 ` João Távora
2022-11-29 21:18 ` Stefan Monnier [this message]
2022-11-29 22:59 ` João Távora
2022-11-29 23:44 ` Stefan Monnier
2022-12-03 13:21 ` João Távora
2022-12-03 14:04 ` Stefan Monnier
2022-12-03 23:22 ` João Távora
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