doomemacs/modules/editor/format/README.org

#+title:    :editor format
#+subtitle: Standardize your ugly code
#+created:  July 26, 2020
#+since:    21.12.0

* Description :unfold:
Code style is something that's hotly debated since the beginning of time.

Tabs or spaces?
2-width or 4-width indentation?

Which is right? Doom doesn't care, but we will try and make it easy for you to
format code within the safety of Emacs.

At present, the module wraps [[https://github.com/radian-software/apheleia/][apheleia]], which includes some more detail on the
internals of the package; but the long and short of it is on-save your code will
be formatted and returned to the buffer using
[[https://tools.ietf.org/doc/tcllib/html/rcs.html#section4][RCS patching]].

** Maintainers
- [[doom-user:][@elken]]

[[doom-contrib-maintainer:][Become a maintainer?]]

** Module flags
- +onsave ::
  Enable reformatting of a buffer when it is saved. See
  [[var:+format-on-save-disabled-modes]] to control what major modes to (or not to)
  format on save.

** Packages
- [[doom-package:apheleia]]

** Hacks
As of writing this, apheleia doesn't /yet/ support regions or similar kinds of
buffers, so there are a couple of hacks to attempt to rectify this.

For the most part, things should work as expected. However, because the
formatting occurs on an isolated version of the buffer; lisp/scheme or similarly
indentation-based languages may produce poor results.

** TODO Changelog
# This section will be machine generated. Don't edit it by hand.
/This module does not have a changelog yet./

* Installation
[[id:01cffea4-3329-45e2-a892-95a384ab2338][Enable this module in your ~doom!~ block.]]

This module has no direct requirements, but each language will need one of their
supported formatter programs in order for this to work. In their absence,
[[doom-package:apheleia]] will fail silently.

To see if a particular mode has a configured formatter, check for the mode in
[[var:apheleia-mode-alist]] which corresponds to the list of formatters defined in
[[var:apheleia-formatters]]

* Usage
** With +onsave
When this flag is enabled, you shouldn't need to do anything other than write
code and save it.

** Without +onsave
Without the flag, formatting will only occur when either =apheleia-format-buffer=
or =+format/buffer= is called.

* Configuration

Detailed configuration can be found [[https://github.com/radian-software/apheleia/#user-guide][upstream]], but for most purposes here we
provide a simple macro that looks like the below:

#+begin_src emacs-lisp
(set-formatter! 'unique-name '("command" "line" "here") :modes '(name-of-major-mode))
#+end_src

If you're trying to override a formatter that has previously been defined by
Doom, you will need to ensure that the call in your config is contained within
an =after!= form, eg below to override Clojure's with =zprint=:

#+begin_src emacs-lisp
(after! clojure-mode
  (set-formatter! 'zprint '("zprint" "-") :modes '(clojure-mode)))
#+end_src

There are a few bonus symbols that apheleia uses (for example =npx= will be
replaced by a correct path to npx) which are all documented in the link above.

** Disabling formatters
*** Permanently
To permanently disable a particular formatter with no provided alternative

#+begin_src emacs-lisp
(setq apheleia-formatters (delq (assoc 'csharpier apheleia-formatters) apheleia-formatters))
#+end_src

*** Per-buffer
If you want to save without formatting, this is done by first passing the
universal argument thus; =SPC u SPC f s= for evil users, =C-u C-x C-s= for non-evil
users.

If you want to save more than a handful of time, you can set
[[var:apheleia-inhibit]] to disable even if =apheleia-global-mode= is on.

*** Onsave only
This behaviour is controlled via [[var:+format-on-save-disabled-modes]] thus;

#+begin_src emacs-lisp
(setq +format-on-save-disabled-modes
      '(emacs-lisp-mode  ; elisp's mechanisms are good enough
        sql-mode         ; sqlformat is currently broken
        tex-mode         ; latexindent is broken
        latex-mode))
#+end_src

In this case, =emacs-lisp-mode=, =sql-mode=, =tex-mode= and =latex-mode= will not be
formatted on save, but can still be formatted by manually invoking the commands
=apheleia-format-buffer= or =+format/buffer=.

** Disabling the LSP formatter
If you are in a buffer with ~lsp-mode~ enabled and a server that supports
=textDocument/formatting=, it will be used instead of [[doom-package:format-all]]'s formatter.

+ To disable this behavior universally use: ~(setq +format-with-lsp nil)~
+ To disable this behavior in one mode: ~(setq-hook! 'python-mode-hook
  +format-with-lsp nil)~

** Selecting a specific formatter for a particular buffer
Set the buffer-local variable ~+format-with~ to the name of the formatter to
use. e.g.
#+begin_src emacs-lisp
;; Overrides `apheleia-mode-alist`
(setq-hook! 'python-mode-hook +format-with 'html-tidy)

;; Or set it to `nil' to fallback to `apheleia-mode-alist`
(setq-hook! 'python-mode-hook +format-with nil)
#+end_src

Formatters are referred to by the name they were defined with. They can be
looked up in the ~apheleia-mode-alist~ hash table.

* Troubleshooting
There are a few fail-safes apheleia has to prevent accidental code wipe,
included silently failing if the command errors or doesn't exist.

Check that the command you've specified runs fine in a terminal first before
reporting this as an issue.

If any errors are reported from the command, run =apheleia-goto-error= to jump to
the error buffer and handle any problems raised there.

Any issues specific to apheleia should most often be reported upstream [[https://github.com/radian-software/apheleia/issues][here]].

* Frequently asked questions
/This module has no FAQs yet./ [[doom-suggest-faq:][Ask one?]]

* TODO Appendix
#+begin_quote
 󱌣 This module has no appendix yet. [[doom-contrib-module:][Write one?]]
#+end_quote