A series of notes that I learn Emacs hacking. Introduction to evil-mode, packages to augment evil, such as evil-leader, eveil-surrond, evil-nerd-commenter, powerline-evil; misc. improvement, such as window-numbering, which-key and powerline packages.

Use Evil to enable vim editing

• aka “Extensible vi layer for Emacs”.
• package-install evil-mode
• In the init-packages.el, add the configuration below

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(evil-mode 1)
(setcdr evil-insert-state-map nil)
(define-key evil-insert-state-map [escape] 'evil-normal-state)

• Some difference between vim and evil-mode

C-d to page down, but C-u does not page up. Because C-u is used as “Universal args” in Emacs. We can change this in customize-group

• PDF manual for user switching from vim to Emacs. Evil.pdf.
• Evil state = Emacs mode
  • evil normal state
  • evail insert state
  • evil visual state
  • evil motion state
  • evil emacs state
  • evil operator state (diw)

We want to set the evil state when we enter certain mode, use the following code

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(dolist (mode '(ag-mode
		flycheck-error-list-mode
		occur-mode
		git-rebase-mode
		))
  (add-to-list 'evil-emacs-state-mode mode))

• Enable key binding in certain mode

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(add-hook 'occur-mode-hook (lambda ()
			     (evil-add-hjkl-bindings occur-mode-map 'emacs
			      (kbd "/") 'evil-search-forward
			      (kbd "n") 'evil-search-next
			      (kbd "N") 'evil-search-previous
			      (kbd "C-d") 'evil-scroll-down
			      (kbd "C-u") 'evil-scroll-up
			      )))

• Add more plugins to customize evil.

  • evil-leader. (global-evil-leader-mode) Helps to add short key to evil normal state. Add as much key bindings as you like.

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    (evil-leader/set-keyword
     "ff" 'find-file
     "fr" 'recentf-open-files
     "bs" 'switch-to-buffer
     "bk" 'kill-buffer
     "pf" 'counsel-git
     "ps" 'helm-do-ag-project-root
     "0" 'select-window-0
     "1" 'select-window-1
     "2" 'select-window-2
     "3" 'select-window-3
     "w/" 'split-window-right
     "w-" 'split-window-below
     "wo" 'delete-other-windows
     ":" 'counsel-M-x
     )
    

  • evil-surround package. When you select a word and type something, the word will be surrounded by that.
  • evil-nerd-commenter package. We can add comment or remove the comment of current section. Add toggle comment line to visual state and normal state:

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(define-key evil-normal-state-map (kbd ",/") 'evilnc-comment-or-uncomment-lines)
(define-key evil-visual-state-map (kbd ",/") 'evilnc-comment-or-uncomment-lines)

• powerline-evil package. A powerline minor mode for the evil mode. Try to add window number to the powerline, but failed. In the video, window numbering is finally enabled without loading the powerline.

Miscellaneous improvement

Use C-w to delete a word backward

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(global-set-key (kbd "C-w") 'backward-kill-word)

window-numbering package

• package-install window-numbering
• (window-numbering-mode 1)

powerline package

• Polish the mode line, make it special and beautiful.
• (require 'powerline)
• (powerline-default-theme)

which-key package

• Installation:

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(require which-key)
(which-key-mode 1)

• Set popup window properties

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(setq which-key-side-window-max-height 0.25)
(setq which-key-side-window-location 'right)

Search in org agenda

• C-a enter agenda mode.
• s to search.
• Read the key in list for details.