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bug#50470: 27.1; 'company-mode' 'eshell'
From: |
Stefan Monnier |
Subject: |
bug#50470: 27.1; 'company-mode' 'eshell' |
Date: |
Fri, 10 Dec 2021 08:10:43 -0500 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/29.0.50 (gnu/linux) |
> In my package capf-autosuggest, I run completion-at-point-functions
> somewhat like this:
>
> (let (;; `pcomplete-completions-at-point' may illegally use
> ;; `completion-in-region' itself instead of returning a collection.
> ;; Let's try to outsmart it.
> (completion-in-region-function
> (lambda (start end collection predicate)
> (throw 'illegal-comp-in-region
> (list start end collection :predicate predicate))))
> ;; Prevent `pcomplete-completions-at-point' from inserting a TAB
> (buffer-read-only t))
> ;; `ielm-complete-filename' may illegaly move point
> (save-excursion
> (condition-case nil
> (catch 'illegal-comp-in-region
> (run-hook-wrapped 'completion-at-point-functions ...))
> (buffer-read-only nil))))
>
> This way, old style capf functions are prevented from inserting a TAB or
> moving point.
Hmm... capf itself tries to "solve" that problem in the following way:
(defvar completion--capf-misbehave-funs nil
"List of functions found on `completion-at-point-functions' that
misbehave.
These are functions that neither return completion data nor a completion
function but instead perform completion right away.")
(defvar completion--capf-safe-funs nil
"List of well-behaved functions found on `completion-at-point-functions'.
These are functions which return proper completion data rather than
a completion function or god knows what else.")
(defun completion--capf-wrapper (fun which)
;; FIXME: The safe/misbehave handling assumes that a given function will
;; always return the same kind of data, but this breaks down with
functions
;; like comint-completion-at-point or mh-letter-completion-at-point, which
;; could be sometimes safe and sometimes misbehaving (and sometimes
neither).
(if (pcase which
('all t)
('safe (member fun completion--capf-safe-funs))
('optimist (not (member fun completion--capf-misbehave-funs))))
(let ((res (funcall fun)))
(cond
((and (consp res) (not (functionp res)))
(unless (member fun completion--capf-safe-funs)
(push fun completion--capf-safe-funs))
(and (eq 'no (plist-get (nthcdr 3 res) :exclusive))
;; FIXME: Here we'd need to decide whether there are
;; valid completions against the current text. But this
depends
;; on the actual completion UI (e.g. with the default
completion
;; it depends on completion-style) ;-(
;; We approximate this result by checking whether prefix
;; completion might work, which means that non-prefix
completion
;; will not work (or not right) for completion functions that
;; are non-exclusive.
(null (try-completion (buffer-substring-no-properties
(car res) (point))
(nth 2 res)
(plist-get (nthcdr 3 res) :predicate)))
(setq res nil)))
((not (or (listp res) (functionp res)))
(unless (member fun completion--capf-misbehave-funs)
(message
"Completion function %S uses a deprecated calling convention"
fun)
(push fun completion--capf-misbehave-funs))))
(if res (cons fun res)))))
(defun completion-at-point ()
"Perform completion on the text around point.
The completion method is determined by `completion-at-point-functions'."
(interactive)
(let ((res (run-hook-wrapped 'completion-at-point-functions
#'completion--capf-wrapper 'all)))
...))
Maybe this should be improved/refined?
Stefan