From Rosetta Code

This the   DELAY.REX   REXX program which emulates the   delay   BIF function as implemented by the PC/REXX and Personal REXX interpreters.

This REXX program (below) will work with most REXXes:

  • PC/REXX   (see note)
  • Personal REXX   (see note)
  • R4 REXX
  • (Microsoft) DOS
  • (Microsoft) Windows
  • any system that supports the PING command

in conjunction with the following program (either external or imbedded).

Note:   when PC/REXX or Personal REXX are used, those REXXes already have a built-in function (BIF), so the   delay   subroutine (below) will never be executed, but the REXX   DELAY   BIF will be used instead.

This REXX program only uses whole seconds   (fractional seconds are ignored).


/*REXX program  delays  (or SLEEPS)  a number of  whole  seconds.       */
trace off /*suppress REXX error msgs.*/
parse arg ! /*obtain all the arguments.*/
if !all(arg()) then exit /*documentation requested? */
if !cms then address '' /*if CMS, use fast cmd path*/
signal on halt /*handle HALT gracefully.*/
signal on noValue /*handle REXX noValue error*/
signal on syntax /*handle REXX syntax errors*/
┌─┘ The DELAY function is used to delay (wait) a specific amount of └─┐
│ (wall-clock) time specified in seconds. Any fraction part is ignored.│
│ │
│ If the REXX program invoking DELAY function is running under PC/REXX │
│ or Personal REXX, this REXX program should never be invoked as those │
└─┐ REXXes have their own built-in function (BIF) named "DELAY". ┌─┘

@cpsleep = 'CP SLEEP' /*point to (CP) SLEEP cmd*/
@ping = 'PING' /*point to the DOS PING cmd*/
parse var ! n _ /*parse argument from parms*/
if _\=='' | arg()>1 then call er 59 /*are there too many args? */
if n=='' then n=1 /*no arg? Then assume 1 sec*/
if \isNum(n) then call er 53,n 'delay-seconds' /*is n numeric? */
n=n%1 /*elide any fractional part*/
if n<=0 then return 0
/* ┌────────────────────┐ */
/* │ delay n seconds. │ */
/* └────────────────────┘ */
when !cms then @cpsleep n%1 "SEC" /*CMS? Use CP SLEEP*/
when !tso then call sleep n%1 /*TSO? Use SLEEP*/
when !regina then call sleep n%1 /*Regina? Use SLEEP*/
when !dos then @ping '-n' n " > NUL" /*DOS? use PING */
otherwise nop
end /*select*/
return 0 /*return a zero value. */
/*═════════════════════════════general 1-line subroutines═══════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════*/
!all:  !!=!;!=space(!);upper !;call !fid;!nt=right(!var('OS'),2)=='NT';!cls=word('CLS VMFCLEAR CLRSCREEN',1+!cms+!tso*2);if arg(1)\==1 then return 0;if wordpos(!,'? ?SAMPLES ?AUTHOR ?FLOW')==0 then return 0;!call=']$H';call '$H' !fn !;!call=;return 1
!cal: if symbol('!CALL')\=="VAR" then !call=; return !call
!env:  !env='ENVIRONMENT'; if !sys=='MSDOS' | !brexx | !r4 | !roo then !env='SYSTEM'; if !os2 then !env='OS2'!env; !ebcdic=1=='f0'x; if !crx then !env='DOS'; return
!fid: parse upper source !sys !fun !fid . 1 . . !fn !ft !fm .; call !sys; if !dos then do; _=lastpos('\',!fn); !fm=left(!fn,_); !fn=substr(!fn,_+1); parse var !fn !fn '.' !ft; end; return word(0 !fn !ft !fm, 1+('0'arg(1)))
!rex: parse upper version !ver !vernum !verdate .; !brexx='BY'==!vernum; !kexx='KEXX'==!ver; !pcrexx='REXX/PERSONAL'==!ver | 'REXX/PC'==!ver; !r4='REXX-R4'==!ver; !regina='REXX-REGINA'==left(!ver,11); !roo='REXX-ROO'==!ver; call !env; return
!sys:  !cms=!sys=='CMS'; !os2=!sys=='OS2'; !tso=!sys=='TSO' | !sys=='MVS'; !vse=!sys=='VSE'; !dos=pos('DOS',!sys)\==0 | pos('WIN',!sys)\==0 | !sys=='CMD'; !crx=left(!sys,6)=='DOSCRX'; call !rex; return
!var: call !fid; if !kexx then return space(dosenv(arg(1))); return space(value(arg(1),,!env))
er: parse arg _1,_2; call '$ERR' "14"p(_1) p(word(_1,2) !fid(1)) _2; if _1<0 then return _1; exit result
p: return word(arg(1),1)
halt: call er .1
isNum: return datatype(arg(1),'N')
noValue: !sigl=sigl; call er 17,!fid(2) !fid(3) !sigl condition('D') sourceline(!sigl)
syntax:  !sigl=sigl; call er 13,!fid(2) !fid(3) !sigl !cal() condition('D') sourceline(!sigl)

Coding note:   the   !   subroutines (above) deal mostly with determining what version of REXX is being invoked and what operating system is being used;   and based on that information, appropriate flags (variables) are set.   This is an example of a robust boilerplate code checking for various versions of REXX and operating systems, and it also defines additional flags not used within this particular program.

Programming note:   The subroutine   $ERR   isn't included here; so here is the gist of the error messages:

  • er 59       too many arguments specified for the ─── DELAY ─── command.
  • er 53       argument ─── xxx ─── isn't numeric for the option ─── delay-seconds ─── for the ─── DELAY ─── command.