fancy-dabbrev

fancy-dabbrev essentially wraps the Emacs built-in dabbrev functionality, with two improvements:

1. Preview: If fancy-dabbrev-mode is enabled, a preview of the first expansion candidate will be shown when any text has been entered. If fancy-dabbrev-expand then is called, the candidate will be expanded.
2. Popup menu: The first call to fancy-dabbrev-expand will expand the entered word prefix just like dabbrev-expand. But the second call will show a popup menu with other candidates (with the second candidate selected). The third call will advance to the third candidate, etc. It is also possible to go back to a previous candidate by calling fancy-dabbrev-backward. Selection from the menu can be canceled with C-g. Any cursor movement or typing will hide the menu again.

Example

After typing "defi":

After pressing TAB (assuming it is bound to fancy-dabbrev-expand):

After pressing TAB a second time:

The menu entries are by default sorted on proximity. This can changed with the fancy-dabbrev-sort-menu configuration option.

After pressing TAB a third time:

After pressing space:

Installation

fancy-dabbrev depends on the popup package, so you need to install that first if you don't have it already.

To load fancy-dabbrev itself, store fancy-dabbrev.el in your Emacs load path and put something like this in your Emacs configuration file:

;; Load fancy-dabbrev.el:
(require 'fancy-dabbrev)

;; Enable fancy-dabbrev previews everywhere:
(global-fancy-dabbrev-mode)

;; Bind fancy-dabbrev-expand and fancy-dabbrev-backward to your keys of
;; choice, here "TAB" and "Shift+TAB":
(global-set-key (kbd "TAB") 'fancy-dabbrev-expand)
(global-set-key (kbd "<backtab>") 'fancy-dabbrev-backward)

;; If you want TAB to indent the line like it usually does when the cursor
;; is not next to an expandable word, use 'fancy-dabbrev-expand-or-indent
;; instead of `fancy-dabbrev-expand`:
(global-set-key (kbd "TAB") 'fancy-dabbrev-expand-or-indent)
(global-set-key (kbd "<backtab>") 'fancy-dabbrev-backward)

Configuration

fancy-dabbrev-expand uses dabbrev-expand under the hood, so most dabbrev-* configuration options affect fancy-dabbrev-expand as well. For instance, if you want to use fancy-dabbrev-expand when programming, you probably want to use these settings:

;; Let dabbrev searches ignore case and expansions preserve case:
(setq dabbrev-case-distinction nil)
(setq dabbrev-case-fold-search t)
(setq dabbrev-case-replace nil)

Here are fancy-dabbrev's own configuration options:

• fancy-dabbrev-expansion-context (default: 'after-symbol)

  Where to try to perform expansion. If 'after-symbol, only try to expand after a symbol (as determined by thing-at-point). If 'after-symbol-or-space, also expand after a space (the first expansion candidate will then be based on the previous symbol). If 'after-non-space, enable expansion after any non-space character. If 'almost-everywhere, enable exansion everywhere except at empty lines.

• fancy-dabbrev-expansion-on-preview-only (default: nil)

  Only expand when a preview is shown or expansion ran for the last command. This has the advantage that fancy-dabbrev-expand-or-indent always falls back to calling fancy-dabbrev-indent-command when there is nothing to expand.

• fancy-dabbrev-indent-command (default: 'indent-for-tab-command)

  The indentation command used for fancy-dabbrev-expand-or-indent.

• fancy-dabbrev-menu-height (default: 10)

  How many expansion candidates to show in the menu.

• fancy-dabbrev-no-expansion-for (default: '(multiple-cursors-mode))

  A list of variables which, if bound and non-nil, will inactivate fancy-dabbrev expansion. The variables typically represent major or minor modes. When inactive, fancy-dabbrev-expand will fall back to running dabbrev-expand.

• fancy-dabbrev-no-preview-for (default: '(iedit-mode isearch-mode multiple-cursors-mode))

  A list of variables which, if bound and non-nil, will inactivate fancy-dabbrev preview. The variables typically represent major or minor modes.

• fancy-dabbrev-preview-context (default: 'at-eol)

  When to show the preview. If 'at-eol, only show the preview if no other text (except whitespace) is to the right of the cursor. If 'before-non-word, show the preview whenever the cursor is not immediately before (or inside) a word. If 'everywhere, always show the preview after typing.

• fancy-dabbrev-preview-delay (default: 0.0)

  How long (in seconds) to wait until displaying the preview after a keystroke. Set this to e.g. 0.2 if you think that it's annoying to get a preview immediately after writing some text.

• fancy-dabbrev-self-insert-commands (default '(self-insert-command org-self-insert-command))

  A list of commands after which to show a preview.

• fancy-dabbrev-sort-menu (default nil)

  If nil, the popup menu will show matching candidates in the order that repeated calls to dabbrev-expand would return (i.e., first candidates before the cursor, then after the cursor and then from other buffers). If t, the candidates (except the first one) will be sorted.

Why?

There are many other Emacs packages for doing more or less advanced auto-completion in different ways. After trying out some of the more popular ones and not clicking with them, I kept coming back to dabbrev due to its simplicity. Since I missed the preview feature and a way of selecting expansions candidates from a menu if the first candidate isn't the right one, I wrote fancy-dabbrev.

Have fun!

/Joel Rosdahl [email protected]