@c -*-texinfo-*-
@c This is part of the GNU Emacs Lisp Reference Manual.
-@c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998 Free Software Foundation, Inc.
+@c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999
+@c Free Software Foundation, Inc.
@c See the file elisp.texi for copying conditions.
@setfilename ../info/markers
@node Markers, Text, Positions, Top
@node Overview of Markers
@section Overview of Markers
- A marker specifies a buffer and a position in that buffer. The marker
-can be used to represent a position in the functions that require one,
-just as an integer could be used. @xref{Positions}, for a complete
-description of positions.
+ A marker specifies a buffer and a position in that buffer. The
+marker can be used to represent a position in the functions that
+require one, just as an integer could be used. In that case, the
+marker's buffer is normally ignored. Of course, a marker used in this
+way usually points to a position in the buffer that the function
+operates on, but that is entirely the programmer's responsibility.
+@xref{Positions}, for a complete description of positions.
A marker has two attributes: the marker position, and the marker
buffer. The marker position is an integer that is equivalent (at a
@end defun
@node Creating Markers
-@section Functions That Create Markers
+@section Functions that Create Markers
When you create a new marker, you can make it point nowhere, or point
to the present position of point, or to the beginning or end of the
accessible portion of the buffer, or to the same place as another given
marker.
+The next four functions all return markers with insertion type
+@code{nil}. @xref{Marker Insertion Types}.
+
@defun make-marker
This function returns a newly created marker that does not point
anywhere.
@end example
@end defun
-@defun copy-marker marker-or-integer insertion-type
+@defun copy-marker marker-or-integer &optional insertion-type
If passed a marker as its argument, @code{copy-marker} returns a
new marker that points to the same place and the same buffer as does
@var{marker-or-integer}. If passed an integer as its argument,
@end example
@end defun
+@defun buffer-has-markers-at position
+@tindex buffer-has-markers-at
+This function returns @code{t} if one or more markers
+point at position @var{position} in the current buffer.
+@end defun
+
@node Marker Insertion Types
@section Marker Insertion Types
relocating a marker to point after the inserted text.
@defun set-marker-insertion-type marker type
-@tindex set-marker-insertion-type
This function sets the insertion type of marker @var{marker} to
@var{type}. If @var{type} is @code{t}, @var{marker} will advance when
text is inserted at its position. If @var{type} is @code{nil},
@end defun
@defun marker-insertion-type marker
-@tindex marker-insertion-type
This function reports the current insertion type of @var{marker}.
@end defun
+Most functions that create markers, without an argument allowing to
+specify the insertion type, create them with insertion type
+@code{nil}. Also, the mark has, by default, insertion type
+@code{nil}.
+
@node Moving Markers
@section Moving Marker Positions
maximum number of entries in the mark ring; once the list becomes this
long, adding a new element deletes the last element.
+ There is also a separate global mark ring, but that is used only in a
+few particular user-level commands, and is not relevant to Lisp
+programming. So we do not describe it here.
+
@defun mark &optional force
@cindex current buffer mark
This function returns the current buffer's mark position as an integer.
-If the mark is inactive, @code{mark} normally signals an error.
-However, if @var{force} is non-@code{nil}, then @code{mark} returns the
-mark position anyway---or @code{nil}, if the mark is not yet set for
-this buffer.
+If Transient Mark mode is enabled, @code{mark-even-if-inactive} is
+@code{nil} and and the mark is inactive, @code{mark} normally signals
+an error. However, if @var{force} is non-@code{nil}, then @code{mark}
+returns the mark position anyway---or @code{nil}, if the mark is not
+yet set for this buffer.
@end defun
@defun mark-marker
Transient Mark mode is enabled). All the primitives that change the
buffer set @code{deactivate-mark}, to deactivate the mark when the
command is finished.
+
+To write Lisp code that modifies the buffer without causing
+deactivation of the mark at the end of the command, bind
+@code{deactivate-mark} to @code{nil} around the code that does the
+modification. For example:
+
+@example
+(let (deactivate-mark)
+ (insert " "))
+@end example
@end defvar
@defun deactivate-mark
@example
@group
mark-ring
-@result{} (#<marker at 11050 in markers.texi>
+@result{} (#<marker at 11050 in markers.texi>
#<marker at 10832 in markers.texi>
@dots{})
@end group
only those functions specifically related to the region itself are
described here.
+The next two functions signal an error if the mark does not point
+anywhere. If Transient Mark mode is enabled and
+@code{mark-even-if-inactive} is @code{nil}, they also signal an error
+if the mark is inactive.
+
@defun region-beginning
This function returns the position of the beginning of the region (as
an integer). This is the position of either point or the mark,
whichever is smaller.
-
-If the mark does not point anywhere, an error is signaled.
@end defun
@defun region-end
This function returns the position of the end of the region (as an
integer). This is the position of either point or the mark, whichever is
larger.
-
-If the mark does not point anywhere, an error is signaled.
@end defun
Few programs need to use the @code{region-beginning} and
to find the beginning and end of the region. This lets other Lisp
programs specify the bounds explicitly as arguments. (@xref{Interactive
Codes}.)
+
+@ignore
+ arch-tag: b1ba2e7a-a0f3-4c5e-875c-7d8e22d73299
+@end ignore