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.

For non-Regina REXXes,   this REXX program only uses whole seconds   (fractional seconds are ignored).


<lang rexx> select

 when !cms     then @cpsleep   n    "SEC"        /*Is this  CMS?      Use   CP SLEEP.  */
 when !tso     then call sleep n                 /*Is this  TSO?      Use   SLEEP cmd. */
 when !regina  then do                           /*Is this Regina?                     */
                    if nFrac=n  then call sleep n                     /*whole seconds? */
                                else call beep 32767, nFrac * 1000    /*uses fraction. */
                                                 /* [↑]  sound MAY be heard, faint tic.*/
 when !dos     then @ping  @pingArgs             /*Is this  DOS?    Use  PING  command.*/
 otherwise          nop                          /*don't know what this environment is.*/
 end   /*select*/

return 0 /*return a zero value (if a function).*/

halt: return 1 /*return a zero value (if a function).*/

/*══════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════*/ !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=3=='f3'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)</lang>

Coding note:   the   !xxx   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.