(Text Representations): Clarify position-bytes.

[gnu-emacs] / lispref / abbrevs.texi

diff --git a/lispref/abbrevs.texi b/lispref/abbrevs.texi
index d586d0bbc1339e49a87da3501c1764b69d1d99b6..a58064ab387d08dff4084c36048db9a52e30852a 100644 (file)
--- a/lispref/abbrevs.texi
+++ b/lispref/abbrevs.texi
@@ -1,6 +1,6 @@
 @c -*-texinfo-*-
 @c This is part of the GNU Emacs Lisp Reference Manual.
 @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
 @c   Free Software Foundation, Inc.
 @c See the file elisp.texi for copying conditions.
 @setfilename ../info/abbrevs


@@ -269,10 +269,10 @@ returns @code{nil} even though expansion did occur.
 @end deffn
 
 @deffn Command abbrev-prefix-mark &optional arg
 @end deffn
 
 @deffn Command abbrev-prefix-mark &optional arg

-This command marks current point as the beginning of an abbrev.  The
-next call to @code{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.
+This command marks the current location of point as the beginning of
+an abbrev.  The next call to @code{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.

 
 First, this command expands any abbrev before point, unless @var{arg}
 is non-@code{nil}.  (Interactively, @var{arg} is the prefix argument.)
 
 First, this command expands any abbrev before point, unless @var{arg}
 is non-@code{nil}.  (Interactively, @var{arg} is the prefix argument.)


@@ -288,7 +288,7 @@ expansion.
 @end defopt
 
 @defvar abbrev-start-location
 @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
 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
 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
 @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}.

 
 @smallexample
 
 @smallexample

-(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))
+      (expand-abbrev))
+    ;; 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
+                       'foo-mode-pre-abbrev-expand
+                       nil t)))

 @end smallexample
 
 @end smallexample
 

+Note that @code{foo-mode-pre-abbrev-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
 @node Standard Abbrev Tables,  , Abbrev Expansion, Abbrevs
 @comment  node-name,  next,  previous,  up
 @section Standard Abbrev Tables