TACL Reference Manual

Built-In Functions and Variables
HP NonStop TACL Reference Manual—429513-018
9-130
#DELTA Built-In Function
command could then save the former Y register value in another variable level. For
example:
123,456 Uxval$ Uyval$
puts 456 into XVAL, 123 into YVAL, and clears the X and Y registers.
The U command is the complementary function of the Q command.
The V Command
The V (view) command is most commonly used as an aid in debugging #DELTA
macros and, in general, finding out where you are in the buffer.
The V command displays lines of text and indicates where the pointer is. The X value
determines the number of lines displayed by the V command. 1V (or V) displays the
line that includes the current position; 2V displays the line that includes the current
position, plus one line in either direction.
The number of lines to display is actually determined by the number of end-of-line
characters encountered in either direction from the current position. Note that end-of-
line characters include the ends-of-lines at either end of the current line. If there is no
text in either direction, the V command does not report an error.
If you use the : flag with the V command, #DELTA indicates the beginning (B) or end
(Z) of the buffer, if they are within the range specified with the V command.
The X Command
The X command loads a TACL variable level with a range of text in the buffer. The X
command must be immediately followed by the name of a variable level; the variable
level name must be terminated by a dollar sign.
The range of text can be specified either with an X register value or with X and Y
register values: xX var-name$ loads x number of lines from the buffer into var-
name; y, xX vvar-name$ loads characters from positions y through x into var-
name.
If you precede the X command with the : flag, #DELTA appends the text to that already
in the variable level. Without the colon flag, #DELTA replaces any existing text in the
variable level with text from the buffer.
The Y Command
The Y command reads text from the input file into the buffer. The contents of the X
register indicate the number of lines to read. If there is no value in the X register,
#DELTA reads, or tries to read, all the lines in the file into the buffer (remember that
the buffer is less than 30,000 characters long).
When the Y command succeeds in reading text into the buffer, it loads the number of
lines read into the X register. If the Y command reads past the end of file, it closes the