Exception Handling in JMP 11

v_r

Hi,

Is it possible to use try()/throw() to look for specific JMP exceptions?

I have a scheduler that updates several tables from several dynamic sources.

I would like to catch things like missing files, columns, or incorrect data types and write them to a log.txt so that it's easy for me to look for and fix anything if the scheduler crashes. Similar to try and catch in java.

I know the function log capture() exists, however because I'm using try() the error doesn't get a chance to be written to the log. It just jumps to my catch expressions.

I can post up sample code if needed.

Thanks!

Craige_Hales

The only way to get feedback in the catch expression of a JSL try() function is through the Exception_msg variable, but that variable is not always set to a useful value.  Sometimes it is.  You can use the JSL throw() function to set it, like this:

try( print("hello"); throw("bang!"), show(exception_msg))

"hello"

exception_msg = "bang!";

So you could wrap other JSL that might create an exception with something like this:

myOpen = function({file},

  try(open(file),

    throw("could not open "||file|| " details="||char(exception_msg)))

);

try( myopen("NOSUCHFILE.JMP"), show(exception_msg) );

exception_msg = "could not open NOSUCHFILE.JMP details=.";

Open didn't set the exception_msg (no details, above), but sqrt(string value) does (extra details, below):

mysqrt = function({v},

try(sqrt(v),

  throw("could not sqrt "||v|| "\!ndetails="||char(exception_msg)))

);

try( mysqrt("minus one"), write(exception_msg) );

could not sqrt minus one

details={"Cannot convert argument to a number [or matrix]"(1, "Sqrt", Sqrt /*###*/(v))}

So you don't really need a wrapper for sqrt.  By concatenating the possible exception_msg to your own, more illuminating message, you'll get more details if open is enhanced to return the exception message in the future.  The char() function around the exception_msg converts a non-existent message to a valid string for concatenation.