#+TITLE: DOOM Modules

* Table of Contents :TOC:noexport:
- [[#introduction][Introduction]]
- [[#overview][Overview]]
  - [[#enablingdisabling-modules][Enabling/disabling modules]]
- [[#the-structure-of-a-module][The structure of a module]]
  - [[#configel][config.el]]
  - [[#packagesel][packages.el]]
  - [[#autoloadel-or-autoloadel][autoload.el OR autoload/*.el]]
  - [[#additional-files][Additional files]]
- [[#appendix][Appendix]]

* Introduction
DOOM is comprised of its core files and then its modules. These modules loosely take after Spacemacs' layers, utilizing a small list of macros to manage and configure plugins and DOOM Emacs.

These macros are:

+ Package management
  + ~(featurep! MODULE SUBMODULE)~: returns =t= if =:module submodule= is activated
  + ~(load! NAME)~: loads NAME.el, relative to the current file
  + ~(require! MODULE SUBMODULE &optional RELOAD-P)~: activates a module & loads its config.el
  + ~(package! NAME &key recipe pin)~: declares a package and where to get it
  + ~(depends-on! MODULE SUBMODULE)~: loads a module's packages.el
+ Configuration
  + ~(set! SETTING &rest ARGS)~: safely cross-configure other modules
  + ~(def-package! NAME &rest PLIST)~: configure a package (wrapper around ~use-package~)
  + ~(def-setting! SETTING &rest ARGS)~: defines a setting other modules can ~set!~

The TL;DR of this document is:

+ Modules are comprised of: =config.el=, =packages.el=, either =autoload.el= or =autoload/*.el=, and =+*.el= files; these are all optional.
+ =config.el= is the only file loaded when a module is activated, and is where you configure the module and its plugins.
+ =packages.el= files inform DOOM what plugins to install and where from, using the ~package!~ macro. This macro accepts a MELPA-style recipe plist to specify a location other than the ELPA for fetching plugins.
+ Use ~set!~ to safely cross-configure modules; ~doom/describe-setting~ can help you discover what settings are available.
+ Packages are deferred by default; add ~:demand t~ to their ~def-package!~ declaration to load them immediately.

* Overview
These modules are in their ideal load order.

+ :feature :: Broad modules that bring essential functionality to Emacs as an editor.
+ :completion :: Swappable completion modules for narrowing down candidate lists quickly.
+ :ui :: Modules that affect the DOOM user interface or experience.
+ :tools :: Small modules that add specific, non-essential functionality to Emacs.
+ :lang :: Modules that bring support for a language or group of languages to Emacs.
+ :app :: Opinionated and heavy modules that totally transform Emacs' UI to serve a specific purpose.
+ :private :: Private configuration modules that are untracked by version control (except for my personal one; use it as a reference).

** Enabling/disabling modules
Change the ~doom!~ block in your ~init.el~ file to enable/disable modules on startup. You'll need to restart Emacs.

Don't forget to run ~make~ afterwards to ensure that the needed packages are installed (and unneeded ones are uninstalled).

#+begin_quote
*Remember*: if you've byte-compiled your config, your changes won't take effect
until you recompile or delete the \*.elc files.
#+end_quote

* The structure of a module
Modules are made up of four *optional* parts:

+ config.el :: The heart of a module; loaded when the module is activated.
+ packages.el :: Tells DOOM what packages to install and where from. Isn't loaded until package management commands are used.
+ autoload.el (or autoload/*.el) :: Lazily-loaded functions for that module.
+ +*.el :: Additional config files; not automatically loaded.

** config.el
*config.el* is loaded immediately. It is the only file proactively loaded by the DOOM module system. Additional files must be explicitly loaded using ~load!~.

It should expect dependencies (in =packages.el=) to be installed and available, but shouldn't make assumptions about what modules are activated (use ~featurep!~ for this).

Packages should be configured using ~after!~ or ~def-package!~ (an alias for ~use-package~).

#+BEGIN_SRC emacs-lisp
;; from modules/completion/company/config.el
(def-package! company
  :commands (company-mode global-company-mode company-complete
             company-complete-common company-manual-begin company-grab-line)
  :config
  (setq company-idle-delay nil
        company-tooltip-limit 10
        company-dabbrev-downcase nil
        company-dabbrev-ignore-case nil)
   [...])
#+END_SRC

+ Packages are *deferred* by default: add ~:demand t~ to ~def-package!~ blocks to load them immediately.
+ Use ~featurep!~ to test DOOM module availability
+ Use ~set!~ to cross-configure modules safely, e.g. company backends:

  #+BEGIN_SRC emacs-lisp
;; from modules/lang/python/config.el
(set! :company-backend 'python-mode '(company-anaconda))
#+END_SRC

** packages.el
This file isn't loaded until you use DOOM's package management commands.

Evaluating them should be deterministic, idempotent, and without side-effects (besides updating ~doom-modules~ and ~doom-packages~).

Packages are declared with the ~package!~ macro, e.g.

#+BEGIN_SRC emacs-lisp
;; from modules/lang/org/packages.el
(package! org-bullets)

;; from modules/tools/rotate-text/packages.el
(package! rotate-text :recipe (:fetcher github :repo "debug-ito/rotate-text.el"))
#+END_SRC

The packages.el of another module can loaded with ~depends-on!~:

#+BEGIN_SRC emacs-lisp
;; from modules/feature/file-templates/packages.el
(depends-on! :feature snippets)
#+END_SRC

** autoload.el OR autoload/*.el
Functions in these files are lazily loaded. ~doom/reload-autoloads~ will scan these and produce an =autoloads.el= file, which tells Emacs where to find these functions.

For example:

#+BEGIN_SRC emacs-lisp
;; from modules/lang/org/autoload/org.el
;;;###autoload
(defun +org/toggle-checkbox ()
  (interactive)
  [...])

;; from modules/lang/org/autoload/evil.el
;;;###autoload (autoload '+org:attach "lang/org/autoload/evil" nil t)
(evil-define-command +org:attach (&optional uri)
  (interactive "<a>")
  [...])
#+END_SRC

Autoload files named ~evil*.el~ will be ignored if =:feature evil= isn't loaded.

** Additional files
The only convention is to prefix additional elisp files with a =+=, e.g.
=modules/feature/version-control/+git.el=.

These are /not/ loaded automatically. Use ~load!~ from ~config.el~ to do so.

#+BEGIN_SRC emacs-lisp
;; from modules/feature/version-control/config.el
(load +git)
#+END_SRC

* Appendix
+ Macros
  + ~(featurep! CATEGORY MODULE)~
  + ~(load! NAME)~
  + ~(package! NAME &key recipe pin)~
  + ~(require! CATEGORY MODULE &optional RELOAD-P)~
  + ~(def-package! NAME &rest PLIST)~
  + ~(set! SETTING &rest ARGS)~
  + ~(def-setting! NAME ARGLIST &rest BODY)~
+ Commands
  + ~doom/reload~
  + ~doom/reload-autoloads~
  + ~doom/compile~
  + ~doom/recompile~
  + ~doom/compile-lite~
  + ~doom/clean-cache~
  + ~doom/clean-compiled~