160 lines
7.8 KiB
EmacsLisp
160 lines
7.8 KiB
EmacsLisp
;;; early-init.el -*- lexical-binding: t; -*-
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;;; Commentary:
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;;
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;; early-init.el was introduced in Emacs 27.1 and is loaded before init.el;
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;; before Emacs initializes package.el and its UI; and before site files are
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;; loaded. This is the best time to tweak Emacs (though any UI work will have to
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;; be deferred).
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;;
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;; This file is responsible for bootstrapping an interactive session, and is
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;; where all our dirtiest (and config-agnostic) startup hacks should live. It's
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;; also home to Doom's bootloader, which lets you choose what Emacs config to
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;; load with one of two switches:
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;; - '--init-directory DIR' (backported from Emacs 29)
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;; - Or Doom's profile system with '--profile NAME' (you declare configs in
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;; $EMACSDIR/profiles.el or implicitly as directories in $EMACSDIR/profiles/).
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;;
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;; You should *never* load this file in non-interactive sessions (e.g. batch
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;; scripts). Load `core-start' or use 'doom run' instead!
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;;
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;;; Code:
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;; Garbage collection is a big contributor to startup times. This fends it off,
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;; then is reset later by enabling `gcmh-mode'. Not resetting it will cause
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;; stuttering/freezes.
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(setq gc-cons-threshold most-positive-fixnum)
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;; Prioritize old byte-compiled source files over newer sources. It saves us a
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;; little IO time to skip all the mtime checks on each lookup.
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(setq load-prefer-newer nil)
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(unless (or (daemonp)
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init-file-debug)
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(let ((old-file-name-handler-alist file-name-handler-alist))
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;; `file-name-handler-alist' is consulted on each `require', `load' and
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;; various path/io functions. You get a minor speed up by unsetting this.
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;; Some warning, however: this could cause problems on builds of Emacs where
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;; its site lisp files aren't byte-compiled and we're forced to load the
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;; *.el.gz files (e.g. on Alpine).
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(setq-default file-name-handler-alist nil)
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;; ...but restore `file-name-handler-alist' later, because it is needed for
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;; handling encrypted or compressed files, among other things.
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(defun doom-reset-file-handler-alist-h ()
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(setq file-name-handler-alist
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;; Merge instead of overwrite because there may have bene changes to
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;; `file-name-handler-alist' since startup we want to preserve.
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(delete-dups (append file-name-handler-alist
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old-file-name-handler-alist))))
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(add-hook 'emacs-startup-hook #'doom-reset-file-handler-alist-h 101))
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;; Premature redisplays can substantially affect startup times and produce
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;; ugly flashes of unstyled Emacs.
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(setq-default inhibit-redisplay t
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inhibit-message t)
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(add-hook 'window-setup-hook
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(lambda ()
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(setq-default inhibit-redisplay nil
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inhibit-message nil)
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(redisplay)))
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;; Site files tend to use `load-file', which emits "Loading X..." messages in
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;; the echo area, which in turn triggers a redisplay. Redisplays can have a
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;; substantial effect on startup times and in this case happens so early that
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;; Emacs may flash white while starting up.
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(define-advice load-file (:override (file) silence)
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(load file nil :nomessage))
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;; Undo our `load-file' advice above, to limit the scope of any edge cases it
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;; may introduce down the road.
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(define-advice startup--load-user-init-file (:before (&rest _) init-doom)
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(advice-remove #'load-file #'load-file@silence)))
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;;
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;;; Detect `user-emacs-directory'
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;; Prevent recursive profile processing, in case you're loading a Doom profile.
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(unless (boundp 'doom-version)
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;; Not using `command-switch-alist' to process --profile and --init-directory
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;; was intentional. `command-switch-alist' is processed too late at startup to
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;; change `user-emacs-directory' in time.
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;; DEPRECATED Backported from 29. Remove this when 27/28 support is removed.
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(let ((initdir (or (cadr (member "--init-directory" command-line-args))
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(getenv-internal "EMACSDIR"))))
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(when initdir
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;; Discard the switch to prevent "invalid option" errors later.
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(add-to-list 'command-switch-alist (cons "--init-directory" (lambda (_) (pop argv))))
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(setq user-emacs-directory initdir)))
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(let ((profile (or (cadr (member "--profile" command-line-args))
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(getenv-internal "DOOMPROFILE"))))
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(when profile
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;; Discard the switch to prevent "invalid option" errors later.
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(add-to-list 'command-switch-alist (cons "--profile" (lambda (_) (pop argv))))
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;; Then process the requested profile, which should set
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;; `user-emacs-directory'. If it doesn't, then you're essentially using
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;; profiles.el as a glorified, runtime dir-locals.el -- which is fine.
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(let ((profiles-dir (or (getenv-internal "DOOMPROFILESDIR")
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(expand-file-name "profiles/" user-emacs-directory)))
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(profiles-file (expand-file-name "profiles.el" user-emacs-directory)))
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(if (file-exists-p profiles-file)
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(with-temp-buffer
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(let ((coding-system-for-read 'utf-8-auto))
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(insert-file-contents profiles-file))
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(condition-case err
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(dolist (var (or (cdr (assq (intern profile) (read (current-buffer))))
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(user-error "No %S profile found" profile)))
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(if (eq var 'env)
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(dolist (env var) (setenv (car env) (cdr env)))
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(set (car var) (cdr var))))
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(error (error "Failed to parse profiles.el: %s" (error-message-string err)))))
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;; If the profile doesn't exist, then use anything in
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;; $EMACSDIR/profiles/* as implicit profiles. I.e. If a foo profile
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;; doesn't exist, `emacs --profile foo' is equivalent to `emacs
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;; --init-directory $EMACSDIR/profile/foo', if the directory exists.
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(let ((profile-dir (expand-file-name profile profiles-dir)))
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(if (file-directory-p profile-dir)
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(setq user-emacs-directory profile-dir)
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(user-error "No profiles.el to look up %S in" profile))))))))
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;;
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;;; Bootstrap
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;; Let er rip
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(let (init-file)
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;; Load the heart of Doom Emacs
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(if (load (expand-file-name "core/core" user-emacs-directory) t t)
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;; ...and prepare it for an interactive session.
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(setq init-file (expand-file-name "core-start" doom-core-dir))
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;; ...but if that fails, then this is likely not a Doom config.
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(setq early-init-file (expand-file-name "early-init" user-emacs-directory))
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(load early-init-file t t))
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;; We hijack Emacs' initfile resolver to inject our own entry point. Why do
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;; this? Because:
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;;
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;; - It spares Emacs the effort of looking for/loading useless initfiles, like
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;; ~/.emacs and ~/_emacs. And skips ~/.emacs.d/init.el, which won't exist if
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;; you're using Doom (fyi: doom hackers or chemacs users could then use
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;; $EMACSDIR as their $DOOMDIR, if they wanted).
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;; - Later, 'doom sync' will dynamically generate its bootstrap file, which
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;; will be important for Doom's profile system later. Until then, we'll use
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;; core/core-start.el.
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;; - A "fallback" initfile can be trivially specified, in case the
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;; bootstrapper is missing (if the user hasn't run 'doom sync' or is a
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;; first-timer). This is an opportunity to display a "safe mode" environment
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;; that's less intimidating and more helpful than the broken state errors
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;; would've left Emacs in, otherwise.
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;; - A generated config allows for a file IO optimized startup.
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(define-advice startup--load-user-init-file (:filter-args (args) init-doom)
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"Initialize Doom Emacs in an interactive session."
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(list (lambda ()
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(or init-file
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(expand-file-name "init.el" user-emacs-directory)))
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nil ; TODO Replace with safe mode initfile
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(caddr args))))
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;;; early-init.el ends here
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