Commit 73b74087 authored by Luc Teirlinck's avatar Luc Teirlinck

(Abbrev Expansion): `abbrev-start-location' can be an integer or a marker.

(Abbrev Expansion): Replace example for `pre-abbrev-expand-hook'.
parent 9933ae48
@c -*-texinfo-*-
@c This is part of the GNU Emacs Lisp Reference Manual.
@c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1999
@c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1999, 2004
@c Free Software Foundation, Inc.
@c See the file elisp.texi for copying conditions.
@setfilename ../info/abbrevs
......@@ -288,7 +288,7 @@ expansion.
@end defopt
@defvar abbrev-start-location
The value of this variable is a marker pointing to the buffer position
The value of this variable is a buffer position (an integer or a marker)
for @code{expand-abbrev} to use as the start of the next abbrev to be
expanded. The value can also be @code{nil}, which means to use the
word before point instead. @code{abbrev-start-location} is set to
......@@ -331,32 +331,43 @@ 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 @code{expand-abbrev} does, and
so a hook function can be used to change the current abbrev table before
abbrev lookup happens.
abbrev lookup happens. (Although you have to do this carefully. See
the example below.)
@end defvar
The following sample code shows a simple use of
@code{pre-abbrev-expand-hook}. If the user terminates an abbrev with
a punctuation character, the hook function asks for confirmation. It
aborts expansion if the user does not confirm.
@code{pre-abbrev-expand-hook}. It assumes that @code{foo-mode} is a
mode for editing certain files in which lines that start with @samp{#}
are comments. You want to use Text mode abbrevs for those lines. The
regular local abbrev table, @code{foo-mode-abbrev-table} is
appropriate for all other lines. Then you can put the following code
in your @file{.emacs} file. @xref{Standard Abbrev Tables}, for the
definitions of @code{local-abbrev-table} and @code{text-mode-abbrev-table}.
(add-hook 'pre-abbrev-expand-hook 'query-if-not-space)
;; @r{This is the function invoked by @code{pre-abbrev-expand-hook}.}
;; @r{If the user terminated the abbrev with a space, the function does}
;; @r{nothing (that is, it returns so that the abbrev can expand). If the}
;; @r{user entered some other character, this function asks whether}
;; @r{expansion should continue.}
;; @r{The function's return value makes no difference.}
(defun query-if-not-space ()
(if (/= ?\s last-command-char)
(if (not (y-or-n-p "Do you want to expand this abbrev? "))
(error "Not expanding this abbrev"))))
(defun foo-mode-pre-abbrev-expand ()
(when (save-excursion (forward-line 0) (eq (char-after) ?#))
(let ((local-abbrev-table text-mode-abbrev-table)
;; Avoid infinite loop.
(pre-abbrev-expand-hook nil))
;; We have already called `expand-abbrev' in this hook.
;; Hence we want the "actual" call following this hook to be a no-op.
(setq abbrev-start-location (point-max)
abbrev-start-location-buffer (current-buffer))))
(add-hook 'foo-mode-hook
#'(lambda ()
(add-hook 'pre-abbrev-expand-hook
nil t)))
@end smallexample
Note that @code{foo-mode-pre-abbrex-expand} just returns @code{nil}
without doing anything for lines not starting with @samp{#}. Hence
abbrevs expand normally using @code{foo-mode-abbrev-table} as local
abbrev table for such lines.
@node Standard Abbrev Tables, , Abbrev Expansion, Abbrevs
@comment node-name, next, previous, up
@section Standard Abbrev Tables
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