Abbrevs are usually expanded by certain interactive commands,
including self-insert-command. This section describes the
subroutines used in writing such commands, as well as the variables they
use for communication.
Function:abbrev-symbolabbrev &optional table
This function returns the symbol representing the abbrev named
abbrev. The value returned is nil if that abbrev is not
defined. The optional second argument table is the abbrev table
to look it up in. If table is nil, this function tries
first the current buffer's local abbrev table, and second the global
abbrev table.
Function:abbrev-expansionabbrev &optional table
This function returns the string that abbrev would expand into (as
defined by the abbrev tables used for the current buffer). The optional
argument table specifies the abbrev table to use, as in
abbrev-symbol.
Command:expand-abbrev
This command expands the abbrev before point, if any. If point does not
follow an abbrev, this command does nothing. The command returns the
abbrev symbol if it did expansion, nil otherwise.
If the abbrev symbol has a hook function which is a symbol whose
no-self-insert property is non-nil, and if the hook
function returns nil as its value, then expand-abbrev
returns nil even though expansion did occur.
Command:abbrev-prefix-mark&optional arg
Mark current point as the beginning of an abbrev. The next call to
expand-abbrev will use the text from here to point (where it is
then) as the abbrev to expand, rather than using the previous word as
usual.
User Option:abbrev-all-caps
When this is set non-nil, an abbrev entered entirely in upper
case is expanded using all upper case. Otherwise, an abbrev entered
entirely in upper case is expanded by capitalizing each word of the
expansion.
Variable:abbrev-start-location
This is the buffer position for expand-abbrev to use as the start
of the next abbrev to be expanded. (nil means use the word
before point instead.) abbrev-start-location is set to
nil each time expand-abbrev is called. This variable is
also set by abbrev-prefix-mark.
Variable:abbrev-start-location-buffer
The value of this variable is the buffer for which
abbrev-start-location has been set. Trying to expand an abbrev
in any other buffer clears abbrev-start-location. This variable
is set by abbrev-prefix-mark.
Variable:last-abbrev
This is the abbrev-symbol of the most recent abbrev expanded. This
information is left by expand-abbrev for the sake of the
unexpand-abbrev command (see section `Expanding Abbrevs' in The GNU Emacs Manual).
Variable:last-abbrev-location
This is the location of the most recent abbrev expanded. This contains
information left by expand-abbrev for the sake of the
unexpand-abbrev command.
Variable:last-abbrev-text
This is the exact expansion text of the most recent abbrev expanded,
after case conversion (if any). Its value is nil if the abbrev
has already been unexpanded. This contains information left by
expand-abbrev for the sake of the unexpand-abbrev command.
Variable:pre-abbrev-expand-hook
This is a normal hook whose functions are executed, in sequence, just
before any expansion of an abbrev. See section 23.6 Hooks. Since it is a normal
hook, the hook functions receive no arguments. However, they can find
the abbrev to be expanded by looking in the buffer before point.
Running the hook is the first thing that expand-abbrev does, and
so a hook function can be used to change the current abbrev table before
abbrev lookup happens.
The following sample code shows a simple use of
pre-abbrev-expand-hook. If the user terminates an abbrev with a
punctuation character, the hook function asks for confirmation. Thus,
this hook allows the user to decide whether to expand the abbrev, and
aborts expansion if it is not confirmed.
(add-hook 'pre-abbrev-expand-hook 'query-if-not-space)
;; This is the function invoked by pre-abbrev-expand-hook.
;; If the user terminated the abbrev with a space, the function does
;; nothing (that is, it returns so that the abbrev can expand). If the
;; user entered some other character, this function asks whether
;; expansion should continue.
;; If the user answers the prompt with y, the function returns
;; nil (because of the not function), but that is
;; acceptable; the return value has no effect on expansion.
(defun query-if-not-space ()
(if (/= ?\ (preceding-char))
(if (not (y-or-n-p "Do you want to expand this abbrev? "))
(error "Not expanding this abbrev"))))
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