PS> To: scoug-programming@scoug.com
PS> Subject: SCOUG-Programming: Q. Rexx stem variables as parameters?
PS>
PS> ...........................................................
PS>
PS> but I'm writing a library routine so I won't know what the stem
PS> variable's name is.
PS>
PS> ............................................................
PS>
Tell us about these libraries - do you really want ot re-use them that
much?
I suppose you might be using several routines from these libraries,
causing name conflicts between their internal variables vrs.
the ones in the main routine you're writing, but is this certain?
#####################################################################
Pure 'indexed' Queue Approach:
/* REXX - How do you pass stem variables as parameters? */
/* Answer: Use a queue instead of a stem variable. */
/* derived from ps1.cmd */
/* Define 'object' Queue 'AQ' and it's properties */
A = 'AQ'
CALL DefineQ A
/* 2. Show what's in it. */
CALL ShowQ '2-' A
/* 3. Now call a procedure and see if you can display and modify the values. */
/* call stemvar A. Note I'm calling with "A.", not "A". "A" fails too. */
call stemvar A /* Note I'm calling with "A.", not "A". "A" fails too. */
/* 4. Show what's in it after returning. */
CALL ShowQ '4-' A
/* 5. Now call a function and see if you can display, modify and return the val
ues. */
/* say '5a-' stemfunc(A.) "stemfunc()" returns a value. */
say '5a-' stemfunc( A ) /* "stemfunc()" returns a value. */
/* 6. Show what's in the stem variable now. */
CALL ShowQ '6-' A
CALL DelQ A
exit
/*************************************************************/
/* SUBROUTINES FOLLOW */
stemvar: PROCEDURE
/* This might be external */
PARSE ARG X
/* Here, download the values from the Queue */
CALL RXQUEUE 'SET', X
/* It might be good to have a check here that X's value
was a valid queue name, but for now
skip this after all the RXQUEUE 'SET' calls.
*/
xcount = Queued()
DO xcount
PARSE VALUE LINEIN('QUEUE:') WITH itemno ':' xelement.itemno
END
/* Do some things with the queue */
say "3- In StemVar ..."
say '3-' xelement.1
xelement.2 = 'New line 2'
/* Here, relaod the queue */
CALL RXQUEUE 'SET', X
DO index = 1 TO xcount
QUEUE index || ':' || xelement.index
END
say "3-' Exiting ..."
return arg(1).
/*************************************************************/
stemfunc: PROCEDURE
/* This might be external */
PARSE ARG X
/* Here, download the values from the Queue */
CALL RXQUEUE 'SET', X
xcount = Queued()
DO xcount
PARSE VALUE LINEIN('QUEUE:') WITH itemno ':' xelement.itemno
END
/* Do some things to the queue elements */
say "5- In StemFunc ..."
say '5-' xelement.2
xelement.2 = "Hello, World"
/* Here, reload the QUEUE */
CALL RXQUEUE 'SET', X
DO index = 1 TO xcount
QUEUE index || ':' || xelement.index
END
say "5- Exiting ..."
return xelement.2
/**************************************************************
define 'Object' Queue '
**********************************************************/
DefineQ: PROCEDURE
PARSE ARG A
/* 1. Initialize a queue structure. */
DHammer:
SAY 'A is: 'A
TrueName = RXQUEUE( 'CREATE', A)
IF ( TrueName >< A ) THEN
DO
/* Some steps to prevent queue leaks - might need to be */
/* different if program intended to be multitasked. */
CALL RXQUEUE 'Delete', A
CALL RXQUEUE 'Delete', TrueName
SIGNAL DHammer
END
SAY 'Using Queue: 'A
CALL RXQUEUE 'SET', A
/* Stuff values into the queue */
QUEUE 1 || ':' || 'Line 1'
QUEUE 2 || ':' || 'Line 2'
QUEUE 3 || ':' || 'Line 3'
return
/*************************************************************/
DelQ: PROCEDURE
PARSE ARG X
/* Delete the QUEUE when finished with it. */
CALL RXQUEUE 'Delete', X
RETURN
/*************************************************************/
ShowQ: PROCEDURE
PARSE ARG PREFIX X
/* Routine to display elements in the Queue */
CALL RXQUEUE 'SET', X
do Queued()
/* Fanning Through the queue */
PARSE VALUE LINEIN('QUEUE:') WITH itemno ':' xelement.itemno
/* Get index and value off the queue */
say PREFIX || xelement.itemno
/* Doing something with the item taken off the queue */
QUEUE itemno || ':' || xelement.itemno
/* Reloading the item number and value onto the queue */
end /* I indent my "end" statements. :) */
return
/* End of REXX Program */
#############################################################
A simple example of what could be done with 'sed', (Stream Editor):
# File 'Cleanup.SED'
# Lines starting with '#' are comments, SED is too simple
# to cope with comment delimiters in other locations
# (at least officially)
#
# A SED script to clean up an input file
s/Sentence/Line/g
s/ A/ 1/g
s/ B/ 2/g
s/ C/ 3/g
. . .
. . .
. . .
s/GarbageX//g
# The above substitutions default to all lines of the input file.
#
# The above are the important ones for this hypothetical
# example case
#
# now some just to show a little more of sed's capabilities:
#
#
5,81s/GarbageY/Important character string/g
#
# this last one will happen only to lines 5 to 81 of the input file.
#
s@Garbage/Z@GarbageZ@
#
# character following "s" instead of "/" to delimit
# target and substitution strings
#
# continuing with straight substitutions to be made to the file
# SED's "s" command just substitutes first item with second
#
# Just to keep things as simple as possible
# this example does not use any 'Regular Expressions' or
# 'Wild Cards' in the string changed to some other string.
#
# End of File 'Cleanup.SED'
EXAMPLE input, we'll call it InA.txt:
GarbageXSentence A GarbageX
GarbageXSentence B GarbageX
GarbageXSentence C GarbageX
.
.
.
Example output, we'll call it OutB.txt:
Line 1
Line 2
Line 3
.
.
.
Example invocation:
sed -f cleanup.sed < InA.txt > OutB.txt
>>>>>>>>Question for Peter Skye: Does the above look like something
that could chop a lot of clutter out of the Rexx script,
if run before hand?
My suspicion is yes.
Question for Steve Lavine:
I think you raised the question whether queue's and named pipes were
the same. I think you said you had worked with named pipes before.
Do you or anyone else out there remember if named pipes were one way only?
Program A transfers data to program B, but not the other way
around for one case of running a named pipe between A and B?
I think A and B, running at the same time, could both put
things on both ends of some arbitrary external queueh,
and either could take stuff off the top.
Regards,
Dallas E. Legan II
(562) 862 - 4854 ext. '*'
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