CurrentBufferVariables(4)

NAME

@wc, @wl - Extract characters from the current buffer

SYNOPSIS

@wl
@wc

DESCRIPTION

Buffer variables are special in that they can only be queried and cannot be set. Buffer variables allow text to be taken from the current buffer and placed into a variable. Two types of extraction are provided @wl provides a line extraction method, @wc provides a character extraction method.

For example, if the current buffer contains the following text:

Richmond 
Lafayette 
<*>Bloomington                (where <*> is the current point) 
Indianapolis 
Gary 
=* me (BE..) == rigel2 == (c:/data/rigel2.txt) =================== 

The @wl variable allows text from the current buffer to be accessed, a command such as:-

set-variable %line @wl 

would start at the current point in the current buffer and grab all the text up to the end of that line and pass that back. Then it would advance the point to the beginning of the next line. Thus, after the set-variable command executes, the string "Bloomington" is placed in the variable %line and the buffer rigel2 now looks like this:

Richmond 
Lafayette 
Bloomington 
<*>Indianapolis               (where <*> is the current point) 
Gary 
=* me (BE..) == rigel2 == (c:/data/rigel2.txt) =================== 

The buffer command @wc gets the current character in the buffer, it does not change the buffer position. It is important to stress that the cursor position is not modified, in general a macro will interrogate the character under the cursor and then affect the buffer (i.e. by moving the cursor, deleting the character etc.) dependent upon the value of the character returned.

EXAMPLE

The @wc variable provides the most useful mechanism to modify the current buffer. The following example is a macro called super-delete which is bound to <CTRL-del>. The macro deletes characters under the cursor in blocks. If a white space character is under the cursor then all characters up until the next non-white space character are deleted. If a non-white space character is under the cursor then all non-white space characters up until the next white space character are deleted, then the white space is deleted. White space in this context is a SPACE, tab or CR character.

; 
;---    Macro to delete the white space, or if an a word all of the 
;       word until the next word is reached. 
; 
define-macro super-delete 
    !while &not &sin @wc " \t\n" 
        forward-delete-char 
    !done 
    !repeat 
        forward-delete-char 
    !until &or &seq @wc "" &not &sin @wc " \t\n" 
    !return 
!emacro 

global-bind-key super-delete "C-delete" 

SEE ALSO

define-macro(2).

(c) Copyright JASSPA 1999
Last Modified: 1999/08/24
Generated On: 1999/12/01