~iany/ Emacs

Temporary Vi Mode in PowerShell

me@iany.me (Ian Yang) — Sat, 22 Nov 2025 23:17:05 +0800

I miss the feature in readline (Bash/Zsh) where Ctrl+x, Ctrl+v switches to Vi command mode temporarily. In that workflow, entering Insert mode switches back to Emacs mode. PSReadLine has a command ViCommandMode, but binding it directly in Emacs mode will report errors on every key input.

The solution requires handling the mode change event to toggle the global EditMode between Emacs and Vi.

When entering “Insert” mode (the default for Emacs users), we force the mode to Emacs and set up the trigger for the temporary Vi mode. When that trigger (Ctrl+x, Ctrl+v) is fired, we switch the edit mode to Vi and jump to command mode.

Here is the configuration for your $PROFILE:

function OnViModeChange {
if ($args[0] -eq 'Insert') {
Set-PSReadLineOption -EditMode Emacs
Set-PSReadlineKeyHandler -Chord "Ctrl+x,Ctrl+v" -ScriptBlock {
Set-PSReadLineOption -EditMode Vi
[Microsoft.PowerShell.PSConsoleReadLine]::ViCommandMode()
}
# Add other Emacs key bindings here.
# Switching `EditMode` resets key bindings to their defaults.
# Remember to reconfigure them.
# Set-PSReadlineKeyHandler -Chord "Ctrl+w" -Function BackwardKillWord
}
}
Set-PSReadLineOption -ViModeIndicator Script
Set-PSReadLineOption -ViModeChangeHandler $Function:OnViModeChange
Set-PSReadLineOption -EditMode Emacs
# Reuse the function to start Emacs mode
OnViModeChange Insert

Switching EditMode resets key bindings to their defaults. Remember to reconfigure them.

Fix TAB Binding For yasnippet And auto-complete

me@iany.me (Ian Yang) — Sat, 31 Mar 2012 00:00:00 +0000

There are two TAB’s in Emacs, (kbd "TAB") (\t, [9]) and (kbd "<tab>") ([tab]). If modes like yasnippet and auto-complete want to bind on TAB, their trigger key must be the same with the original Tab command. Since Emacs binds indent-for-tab-command on (kbd "TAB"), so it’s better to use it as the trigger key. Yasnippet binds to it by default, It is also easy to setup auto-complete to trigger using Tab.

;; trigger using TAB and disable auto start
(custom-set-variables
'(ac-trigger-key "TAB")
'(ac-auto-start nil)
'(ac-use-menu-map t))

But in some modes (ruby-mode, markdown-mode, org-mode), the command is bind to (kbd "<tab>"), when the real Tab key is typed, the function bind on (kbd "<tab>) has higher priority, so yasnippet and auto-complete are not invoked. It is easy to fix by moving the keybinding:

(defun iy-tab-noconflict ()
(let ((command (key-binding [tab]))) ; remember command
(local-unset-key [tab]) ; unset from (kbd "<tab>")
(local-set-key (kbd "TAB") command))) ; bind to (kbd "TAB")
(add-hook 'ruby-mode-hook 'iy-ac-tab-noconflict)
(add-hook 'markdown-mode-hook 'iy-ac-tab-noconflict)
(add-hook 'org-mode-hook 'iy-ac-tab-noconflict)

Use Popup isearch For Yasnippet Prompt

me@iany.me (Ian Yang) — Fri, 30 Mar 2012 00:00:00 +0000

Yasnippet tries functions in yas/prompt-functions when it needs user to select one choice, such as selecting snippets with the same trigger key, such as helper method yas/choose-value.

popup is a visual popup interface library extracted from auto-complete by its author. It has better look and feel than all the built-in yas/prompt-functions. Also it is easy to customize, and its isearch mode is very efficient, the items are filtered on-the-fly when typing.

The integration is easy. Load popup.el, implement one prompt function and add it to yas/prompt-functions.

※ yasnippet-popup-isearch-prompt.el

(require 'popup)
(require 'yasnippet)
;; add some shotcuts in popup menu mode
(define-key popup-menu-keymap (kbd "M-n") 'popup-next)
(define-key popup-menu-keymap (kbd "TAB") 'popup-next)
(define-key popup-menu-keymap (kbd "<tab>") 'popup-next)
(define-key popup-menu-keymap (kbd "<backtab>") 'popup-previous)
(define-key popup-menu-keymap (kbd "M-p") 'popup-previous)
(defun yas/popup-isearch-prompt (prompt choices &optional display-fn)
(when (featurep 'popup)
(popup-menu*
(mapcar
(lambda (choice)
(popup-make-item
(or (and display-fn (funcall display-fn choice))
choice)
:value choice))
choices)
:prompt prompt
;; start isearch mode immediately
:isearch t
)))
(setq yas/prompt-functions '(yas/popup-isearch-prompt yas/no-prompt))

Highlight Ruby New Hash In Emacs

me@iany.me (Ian Yang) — Thu, 12 Jan 2012 00:00:00 +0000

Not fully tested, let me know if it mess up your buffer.

※ my-ruby-mode.el

(font-lock-add-keywords
'ruby-mode
'(("\\(\\b\\sw[_a-zA-Z0-9]*:\\)\\(?:\\s-\\|$\\)" (1 font-lock-constant-face))))