20.5.3 Minibuffer Commands that Do Completion

This section describes the keymaps, commands and user options used in the minibuffer to do completion.

Variable: minibuffer-local-completion-map

completing-read uses this value as the local keymap when an exact match of one of the completions is not required. By default, this keymap makes the following bindings:

?

minibuffer-completion-help

SPC

minibuffer-complete-word

TAB

minibuffer-complete

with other characters bound as in minibuffer-local-map (see section 20.2 Reading Text Strings with the Minibuffer).

Variable: minibuffer-local-must-match-map

completing-read uses this value as the local keymap when an exact match of one of the completions is required. Therefore, no keys are bound to exit-minibuffer, the command that exits the minibuffer unconditionally. By default, this keymap makes the following bindings:

?

minibuffer-completion-help

SPC

minibuffer-complete-word

TAB

minibuffer-complete

C-j

minibuffer-complete-and-exit

RET

minibuffer-complete-and-exit

with other characters bound as in minibuffer-local-map.

Variable: minibuffer-completion-table

The value of this variable is the alist or obarray used for completion in the minibuffer. This is the global variable that contains what completing-read passes to try-completion. It is used by minibuffer completion commands such as minibuffer-complete-word.

Variable: minibuffer-completion-predicate

This variable's value is the predicate that completing-read passes to try-completion. The variable is also used by the other minibuffer completion functions.

Command: minibuffer-complete-word

This function completes the minibuffer contents by at most a single word. Even if the minibuffer contents have only one completion, minibuffer-complete-word does not add any characters beyond the first character that is not a word constituent. See section 35. Syntax Tables.

Command: minibuffer-complete

This function completes the minibuffer contents as far as possible.

Command: minibuffer-complete-and-exit

This function completes the minibuffer contents, and exits if confirmation is not required, i.e., if minibuffer-completion-confirm is nil. If confirmation is required, it is given by repeating this command immediately--the command is programmed to work without confirmation when run twice in succession.

Variable: minibuffer-completion-confirm

When the value of this variable is non-nil, Emacs asks for confirmation of a completion before exiting the minibuffer. The function minibuffer-complete-and-exit checks the value of this variable before it exits.

Command: minibuffer-completion-help

This function creates a list of the possible completions of the current minibuffer contents. It works by calling all-completions using the value of the variable minibuffer-completion-table as the collection argument, and the value of minibuffer-completion-predicate as the predicate argument. The list of completions is displayed as text in a buffer named `*Completions*'.

Function: display-completion-list completions

This function displays completions to the stream in standard-output, usually a buffer. (See section 19. Reading and Printing Lisp Objects, for more information about streams.) The argument completions is normally a list of completions just returned by all-completions, but it does not have to be. Each element may be a symbol or a string, either of which is simply printed, or a list of two strings, which is printed as if the strings were concatenated.

This function is called by minibuffer-completion-help. The most common way to use it is together with with-output-to-temp-buffer, like this:

(with-output-to-temp-buffer "*Completions*" (display-completion-list (all-completions (buffer-string) my-alist)))

User Option: completion-auto-help

If this variable is non-nil, the completion commands automatically display a list of possible completions whenever nothing can be completed because the next character is not uniquely determined.