31.3 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 nil. Voir la section Marker Insertion Types.

Function: make-marker

This function returns a newly created marker that does not point anywhere.

(make-marker) ⇒ #<marker in no buffer>

Function: point-marker

This function returns a new marker that points to the present position of point in the current buffer. Voir la section Point. For an example, see copy-marker, below.

Function: point-min-marker

This function returns a new marker that points to the beginning of the accessible portion of the buffer. This will be the beginning of the buffer unless narrowing is in effect. Voir la section Narrowing.

Function: point-max-marker

This function returns a new marker that points to the end of the accessible portion of the buffer. This will be the end of the buffer unless narrowing is in effect. Voir la section Narrowing.

Here are examples of this function and point-min-marker, shown in a buffer containing a version of the source file for the text of this chapter.

(point-min-marker) ⇒ #<marker at 1 in markers.texi> (point-max-marker) ⇒ #<marker at 15573 in markers.texi> (narrow-to-region 100 200) ⇒ nil (point-min-marker) ⇒ #<marker at 100 in markers.texi> (point-max-marker) ⇒ #<marker at 200 in markers.texi>

Function: copy-marker marker-or-integer &optional insertion-type

If passed a marker as its argument, copy-marker returns a new marker that points to the same place and the same buffer as does marker-or-integer. If passed an integer as its argument, copy-marker returns a new marker that points to position marker-or-integer in the current buffer.

The new marker's insertion type is specified by the argument insertion-type. Voir la section Marker Insertion Types.

If passed an integer argument less than 1, copy-marker returns a new marker that points to the beginning of the current buffer. If passed an integer argument greater than the length of the buffer, copy-marker returns a new marker that points to the end of the buffer.

(copy-marker 0) ⇒ #<marker at 1 in markers.texi> (copy-marker 20000) ⇒ #<marker at 7572 in markers.texi>

An error is signaled if marker is neither a marker nor an integer.

Two distinct markers are considered equal (even though not eq) to each other if they have the same position and buffer, or if they both point nowhere.

(setq p (point-marker))
     ⇒ #<marker at 2139 in markers.texi>

(setq q (copy-marker p))
     ⇒ #<marker at 2139 in markers.texi>

(eq p q)
     ⇒ nil

(equal p q)
     ⇒ t

Ce document a été généré par Eric Reinbold le 13 Octobre 2007 en utilisant texi2html 1.78.