2. Completion functions

The file `light.el' defines several functions that do lightning completion:

• completing-insert-file-name completes on file names.
• completing-insert-buffer-name completes on buffer names.
• completing-insert-lisp-object completes on lisp objects.
• completing-insert-lisp-function completes on lisp functions.
• completing-insert-lisp-variable completes on lisp variables.
• completing-insert-kill completes on the contents of the kill ring.
• completing-insert-buffer-contents completes on the contents of the current buffer, or with a prefix argument on the contents of any specified buffer. See section 6.2 Buffer completion.
• completing-insert-according-to-mode makes a guess as to what sort of completion it should do; if it can't figure it out, it completes on lisp objects. (This one is mainly useful in the minibuffer.)

(These functions all call the function completing-insert, which I'm too lazy to document. The casual user won't want to call it directly, anyway, and the more serious user can figure it out for herself.)

For example, if I'm typing an info page for lightning completion, and I want to insert the string `completing-insert-kill', I run completing-insert-lisp-function, and then use lightning completion to produce the function name, avoiding typing the whole thing in (and also avoiding typos). In detail: once I start completing-insert-lisp-function, the following happens:

• I type the letters c, o, m, p, and Emacs inserts `comp'.
• I type l and pause, and Emacs inserts `let' (so I have `complet' so far).
• I type i and n and pause, and Emacs inserts `ing-' (so I have `completing-' so far).
• I type i and pause, and Emacs inserts `insert' (so I have `completing-insert' so far).
• I type -, and Emacs inserts `-' (so I have `completing-insert-' so far).
• I type k and pause, and Emacs inserts `kill' (so I have `completing-insert-kill', and completion stops).

There are user customizable variables (in the customization group "lightning-completion") related to these functions. If the variable lc-ctrl-x-c-is-completion is non-nil, then C-x c is the prefix key for these commands. This is one of the few global key bindings available, probably because it is too close to C-x C-c. So be warned, if you use these key bindings, you may occasionally hit C-x C-c instead of C-x c. Anyway, enabling this options provides the following key bindings:

C-x c F

runs completing-insert-file-name.

C-x c b

runs completing-insert-buffer-name.

C-x c o

runs completing-insert-lisp-object.

C-x c f

runs completing-insert-lisp-function.

C-x c v

runs completing-insert-lisp-variable.

C-x c k

runs completing-insert-kill.

C-x c y

runs completing-insert-buffer-contents.

C-x c u

runs completing-insert-according-to-mode.

Note that if one plans on using lightning completion only occasionally, and always from the minibuffer, one might be able to get away with only using the function completing-insert-according-to-mode. There is a customizable variable lc-ctrl-backslash-completes-a-la-mode. If it is non-nil, then C-\ runs completing-insert-according-to-mode.