Thanks Bart.

I think that  I was initially not finding what I was expecting when I set up my frills loops and so printed a few things to STDERR to try and figure out what was going on.

That decision to use STDERR seems to have been the cause of the problems that I was seeing - so, like you and Mark, I'll be sending debug info to the division in future!

I see in the XyMacros manual it has this in the Error Handling section on page 6-26:

Note: If you write to STDERR from your Perl program, XPP does not
compose any generated text, but writes the error information to job.log.

I don't think that really covers the behaviour that I was seeing though ... I'll open a ticket to enquire further.

cheers,

Paul

Hi Paul (and Mark and Bart),

I think the "answer" that's indicated by what you quoted from the manual is that if a XyPerl script writes anything to STDERR then that is treated as a composition "error" and anything that the same XyPerl script has written to STDOUT (meant to go back as input to composition) will get ignored ("XPP does not compose any generated text").

In other words, if a XyPerl script at any point during a call writes anything to STDERR then anything that the same call wrote to STDOUT is ignored - even if things were written to STDOUT before the script wrote to STDERR.

The writing to STDERR by a XyPerl script was intended to be used for "abort" types of situations, and not really meant to be a means of "communication".

However, there are some other options that can be used for "debugging" than having to write your messages to STDOUT and have those messages become part of the composed text (thereby interfering with the desired composition results).

1. You can have your XyPerl script write "debugging" messages to a separate file of your choice that you can view later (i.e. do not write these messages to STDOUT or STDERR).

2. You can use the logging macro <lg> (added in XPP 8.4 release) to write a message to the composition log (and dialog window in the XyView). See the documentation on it, but with XyPerl you would craft an <lg;...> macro and then write it to STDOUT. When that is later composed (along with everything else written to STDOUT and as long as nothing is written to STDERR and no error occurs), then composition will write the <lg> message to the composition log and to the message dialog.

Hope that helps.

Hi Jonathan,

Perfect! - Thanks very much for your explanation and guidance - that's very helpful.

I've just tried the $X->lg("message") route in my XyPerl program and that has worked a treat.

cheers,

Paul