This is a follow-up to my first Emacs pro-tips.
Speed up initialization
If you don’t use Emacs daemon or if you develop Emacs, you might find yourself re-starting it a lot. In which case it may be useful to keep startup time to a minimum.
;;; Temporarily reduce garbage collection during startup. Inspect `gcs-done'. (defun ambrevar/reset-gc-cons-threshold () (setq gc-cons-threshold (car (get 'gc-cons-threshold 'standard-value)))) (setq gc-cons-threshold (* 64 1024 1024)) (add-hook 'after-init-hook #'ambrevar/reset-gc-cons-threshold) ;;; Temporarily disable the file name handler. (setq default-file-name-handler-alist file-name-handler-alist) (setq file-name-handler-alist nil) (defun ambrevar/reset-file-name-handler-alist () (setq file-name-handler-alist (append default-file-name-handler-alist file-name-handler-alist)) (cl-delete-duplicates file-name-handler-alist :test 'equal)) (add-hook 'after-init-hook #'ambrevar/reset-file-name-handler-alist)
Avoid the pitfall of “loading old bytecode instead of newer source”
(setq load-prefer-newer t)
Site Lisp folder for local packages and development
We need to roll out our own function since we want the local site folder first
normal-top-level-add-subdirs-to-load-path appends it
to the very end.
(defun ambrevar/package-refresh-load-path (path) "Add every non-hidden sub-folder of PATH to `load-path'." (when (file-directory-p path) (dolist (dir (directory-files path t "^[^\\.]")) (when (file-directory-p dir) (setq load-path (add-to-list 'load-path dir)) (dolist (subdir (directory-files dir t "^[^\\.]")) (when (file-directory-p subdir) (setq load-path (add-to-list 'load-path subdir)))))))) (let ((site-lisp (expand-file-name "site-lisp/" "~/.local/share/emacs/"))) (add-to-list 'load-path site-lisp) (ambrevar/package-refresh-load-path site-lisp))
Flyspell and whitespace-mode
(defun ambrevar/flyspell-and-whitespace-mode () "Toggle `flyspell-mode' and `whitespace-mode'." (interactive) (if (derived-mode-p 'prog-mode) (flyspell-prog-mode) (flyspell-mode) (when flyspell-mode (flyspell-buffer))) (whitespace-mode 'toggle)) (global-set-key (kbd "<f9>") #'ambrevar/flyspell-and-whitespace-mode)
Download video URL at point
The following requires the
(defun ambrevar/youtube-dl-at-point (&optional url) "Run 'youtube-dl' over the URL at point. If URL is non-nil, use that instead." (interactive) (setq url (or url (thing-at-point-url-at-point))) (let ((eshell-buffer-name "*youtube-dl*")) (eshell) (when (eshell-interactive-process) (eshell t)) (eshell-interrupt-process) (insert "cd ~/temp && youtube-dl " url) (eshell-send-input)))
See also youtube-dl-emacs.
List current minor modes
(defun ambrevar/current-minor-modes () "Return the list of minor modes enabled in the current buffer." (interactive) (delq nil (mapcar (lambda (mode) (if (and (boundp mode) (symbol-value mode)) mode)) minor-mode-list)))
Since I use EXWM as a window manager, I can dedicate the
super key to window
Some simple, yet efficient rules:
s-TAB: Switch to last buffer.
s-<hjkl>with Evil): select window in the chosen direction.
S-s-<hjkl>with Evil): swap current window with window in the chosen direction.
s-\: Toggle between horizontal and vertical splitting.
s-o: Toggle-hide all other windows.
With Helm, I use
C-c o (or my custom binding
S-RET) to find a file or a
buffer in a new split window.
I need some extra functions to implement the above workflow:
(defun ambrevar/swap-windows (&optional w1 w2) "If 2 windows are up, swap them. Else if W1 is a window, swap it with current window. If W2 is a window too, swap both." (interactive) (unless (or (= 2 (count-windows)) (windowp w1) (windowp w2)) (error "Ambiguous window selection")) (let* ((w1 (or w1 (car (window-list)))) (w2 (or w2 (if (eq w1 (car (window-list))) (nth 1 (window-list)) (car (window-list))))) (b1 (window-buffer w1)) (b2 (window-buffer w2)) (s1 (window-start w1)) (s2 (window-start w2))) (with-temp-buffer ;; Some buffers like EXWM buffers can only be in one live buffer at once. ;; Switch to a dummy buffer in w2 so that we don't display any buffer twice. (set-window-buffer w2 (current-buffer)) (set-window-buffer w1 b2) (set-window-buffer w2 b1)) (set-window-start w1 s2) (set-window-start w2 s1)) (select-window w1)) (global-set-key (kbd "C-x \\") 'swap-windows) (defun ambrevar/swap-windows-left () "Swap current window with the window to the left." (interactive) (ambrevar/swap-windows (window-in-direction 'left))) (defun ambrevar/swap-windows-below () "Swap current window with the window below." (interactive) (ambrevar/swap-windows (window-in-direction 'below))) (defun ambrevar/swap-windows-above () "Swap current window with the window above." (interactive) (ambrevar/swap-windows (window-in-direction 'above))) (defun ambrevar/swap-windows-right () "Swap current window with the window to the right." (interactive) (ambrevar/swap-windows (window-in-direction 'right))) (defun ambrevar/switch-to-last-buffer () "Switch to last open buffer in current window." (interactive) (switch-to-buffer (other-buffer (current-buffer) 1))) (defun ambrevar/toggle-single-window () "Un-maximize current window. If multiple windows are active, save window configuration and delete other windows. If only one window is active and a window configuration was previously save, restore that configuration." (interactive) (if (= (count-windows) 1) (when single-window--last-configuration (set-window-configuration single-window--last-configuration)) (setq single-window--last-configuration (current-window-configuration)) (delete-other-windows))) (defun ambrevar/toggle-window-split () "Switch between vertical and horizontal split. It only works for frames with exactly two windows." (interactive) (if (= (count-windows) 2) (let* ((this-win-buffer (window-buffer)) (next-win-buffer (window-buffer (next-window))) (this-win-edges (window-edges (selected-window))) (next-win-edges (window-edges (next-window))) (this-win-2nd (not (and (<= (car this-win-edges) (car next-win-edges)) (<= (cadr this-win-edges) (cadr next-win-edges))))) (splitter (if (= (car this-win-edges) (car (window-edges (next-window)))) 'split-window-horizontally 'split-window-vertically))) (delete-other-windows) (let ((first-win (selected-window))) (funcall splitter) (if this-win-2nd (other-window 1)) (set-window-buffer (selected-window) this-win-buffer) (set-window-buffer (next-window) next-win-buffer) (select-window first-win) (if this-win-2nd (other-window 1))))))
Use FreeDesktop.org’s trash
Whenever Emacs “delete” a file (from
dired, Helm Find-Files or Elisp
primitives), tell Emacs to move it to the trash instead:
(setq delete-by-moving-to-trash t)
Lisp parentheses editing
A recurring complaint with Lisp is the need for balancing parentheses.
That is to say, on a blackboard… Since such a task should pose no difficulty to a computer and Emacs can obviously help here!
First, let’s enable parenthesis highlighting. I like to remove the delay so that Emacs highlights the matching parenthesis instantly:
;;; Show matching parenthesis (show-paren-mode 1) ;;; By default, there’s a small delay before showing a matching parenthesis. Set ;;; it to 0 to deactivate. (setq show-paren-delay 0) (setq show-paren-when-point-inside-paren t) (with-eval-after-load 'paren (set-face-background 'show-paren-match "#555555") (set-face-foreground 'show-paren-match "#def") (set-face-attribute 'show-paren-match nil :weight 'extra-bold))
Next, we can install the
rainbow-delimiters third-party package which colors
parentheses according to their depth. This is no more than the moral equivalent
of indenting in C or other members of the Algol family.
Goodbye Paredit, hello Lispy
Consider using Lispy which brings Lisp syntactic editing to a whole new level: beside parenthesis balancing (which makes the previous section superfluous altogether), it offers advanced expression navigation, code transforms, style prettification and more.
Have a looks at the demos for some concrete examples.
If you think about it, Lispy is the obvious evolution of editor support for Lisp editing: it truly exploits the fact that the language syntax is an abstract syntax tree. It would be a shame not to make use of this property.
Image manipulation and thumbnail gallery
A maybe not-so-well-known command is
image-dired: when run in a directory of
pictures, it displays a gallery of thumbnails with previews.
SPC displays the
next picture in another window while
C-RET opens the picture in the
image-dired-external-viewer. It’s possible to rotate files, tag them in dired
or add comments.
image+ third-party package adds extra picture capabilities to Emacs, like
stiky transforms and file modifications.
Don’t use terminal-Emacs
Making music in Emacs
Emacs chart library
Odd nconc behaviour
One of the few oddities in the Elisp language: https://stackoverflow.com/questions/25157349/odd-behaviour-with-nconc-in-emacs-lisp