Here's one I never noticed before. Often I'll do something like: > Do i = 0 Until filelist | (rc ¬= 0) > > 'PIPE rexxvars' i 'nomsg233' , > '| take 1' , > '| strfind ,s_CMS_COMMAND_FILELIST_EXEC_,' , > '| count lines' , > '| var filelist' , > > End
I just had a case where I want to know if the current exec has called itself, so I want to skip level 0. I changed i=0 to i=1 in my loop, and ran into Error 34: Logical value not 0 or 1. Even though the message is suppressed, REXXVARS (as documented) only commits to -1, the rest of the pipeline doesn't run, and my variable never gets set. The obvious workaround in this case is just to set my variable to 0 before starting the loop. If I needed to do more in the pipeline, though, I'd have to wrap REXXVARS in something to mask the failure. PREFACE seems to do the trick, by moving it into a called pipeline: > pipe preface rexxvars 1 nomsg233|count lines|cons > 0 > Ready(00233); Actually, though, looking at the PREFACE doc, I wasn't so sure that was actually safe: > Commit Level: "preface" starts on commit level -1. The subroutine pipeline > must commit to 0 if it generates output. And in fact, if I leave off NOMSG233, it doesn't commit: > pipe preface rexxvars 1|count lines|cons > > No active EXECCOMM environment found. > > ... Processing "callpipe (name Append/Preface stagesep | escape "". > > ... Issued from stage 1 of pipeline 1 name "Append/Preface". > > ... Running "rexxvars 1". > > Ready(00233); > So I guess the simple, safe solution is actually APPEND, which obviously has to commit before it can see EOF on the input: > 'PIPE append rexxvars' i 'nomsg233' etc. But what's going on with PREFACE? Does it detect whether the subroutine pipeline issued any messages, and commit if not? ¬R
