[netrexx-pipelines] On return codes and error messages in pipeline filters

[Colin K <CK-...@im...>]

Hello all.

As I continue my little education into the world of creating filters 
under NetRexx I have some more questions :-)

I notice that a number of the filters contain the statement:

    exit(rc*(rc \= 12))


as the last line in the program.  Where does the value 12 come from and 
what does it represent?  It seems to be a fairly common convention.  The 
only thing I can think of is that is a return that signifies that there 
is no more data in the pipe and that the filter should shut down ??

Is there a list of return codes and their meaning anywhere?


I also notice that some filters, when reporting an error, use Emsg.  For 
example

    Emsg(11,'Error - Input not a rexx object')


Is Emsg specially supposed to be only used in catch statements? Is Emsg 
supposed to be used for any error message that is issued in the run method?

If I catch an error should one use Emsg or output(‘. . .error msg. . .’) 
or just “say”.  I presume ‘say’s get written directly to the console as 
opposed to the primary output stream (which could be the console I 
guess).  Fair statement?

Thanks
Colin