Emacs Completions¶

No Emacs configuration is complete without a lengthy discussion on how completions are handled.

`Completions`¶

I actually quite like the default *Completions* buffer and used it extensively from Emacs 29.1 to around 30.1. (Also seeing how there is a bunch of stuff coming in Emacs 31 I’m sure I will switch back again to it before long! 😅)

My config wasn’t anything particuarly exciting, as I only:

Tweaked some options that control how it is rendered

init.el

(setq completions-detailed t
      completions-format 'one-column
      completions-group t
      completions-header-format (propertize "%s candidates\n" 'face 'shadow)
      completions-max-height 15
      completion-show-help nil)

Tweaked some options that control its behaviour
init.el
```
(setq completion-auto-help 'visible
      completion-auto-select 'second-tab
      completion-cycle-threshold 3)
```
That is to say, the *Completions* buffer only opens on the second attempt at completing something. However, once it is open keep it updated and only focus it on the second completion attempt with no progress made.

If there are only 3 or fewer options, don’t bother with the *Completions* buffer at all.

Finally, use C-n and C-p to cycle through completion candidates.

(dolist (kmap (list minibuffer-local-map completion-in-region-mode-map))
  (keymap-set kmap "C-p" #'minibuffer-previous-completion)
  (keymap-set kmap "C-n" #'minibuffer-next-completion))

However there are occasions where you want just a little bit… more.

Consult¶

Consult, the grab-bag of utility functions built on top of completing-read. I admit, I probably don’t use this as much as I should.

init.el

(use-package consult
  :ensure t
  :custom
  (consult-preview-key "M-.")
  :bind (("C-x b" . consult-buffer)))

I don’t often want the live preview feature, but it’s nice to be able to opt into it by hitting M-.

Embark¶

Orderless¶

Continuing with the established theme I use the orderless completion style as even a basic config is useful, but it would be great to experiment with some style dispatchers!

init.el

(use-package orderless
  :ensure t
  :custom
  (completion-styles '(orderless basic))
  (completion-category-defaults nil)
  (completion-category-overrides '((file (styles basic partial-completion)))))

Vertico¶

See also

VOMPECCC: A Modular Completion Framework for Emacs: The article that pushed me over the edge to actually setting vertico up.

As mentioned in the *Completions* section above, I was really happy with the built-in completions experience. I find the ~95% of the time, I already know what I’m trying to select and I’m only really looking for a bit of tab-completion to save on the typing.

Therefore vertico’s unobtrusive mode is perfect.

To cover that remaining 5%, I can use the multiform extension to switch to a different mode for some pre-determined cases, or on an ad-hoc basis thanks to the vertico-mutliform-map keymap.

So I have arrived at the following config.

init.el

(use-package vertico
  :ensure t
  :init
  (vertico-mode)
  :config

  (setq vertico-multiform-commands
        '((consult-line buffer)))

  (setq vertico-multiform-categories
        '((t unobtrusive)))

  (vertico-multiform-mode t))

The trick was realising I could use (t unobtrusive) as a fallback to active the unobtrusive mode by default!

As for completion-in-region, I still don’t feel the need for something like corfu but I was definitely excited to see the following snippet in vertico’s README.

init.el

(setq completion-in-region-function #'consult-completion-in-region)

So I get to keep my consistent completion experience regardless of what I am completing!

Emacs Completions¶

*Completions*¶

Consult¶

Embark¶

Orderless¶

Vertico¶

`Completions`¶