*Location

In a routine, you can choose to leave the call stack as it is after the error has occurred. To do so, place an asterisk (*) before location and within the double quotes. This form is not valid for use within procedures; attempted to do so results in a <SYNTAX> error. It can only be used in subroutines that are not procedures, as in this example:

Main
   SET $ZTRAP="*OnError"
   WRITE !,"$ZTRAP set to: ",$ZTRAP
  // program code
OnError
   // Error handling code
   QUIT

This format simply causes a GOTO to the line label specified in $ZTRAP; $STACK and $ESTACK are unchanged. The context frame of the $ZTRAP error handling routine is the same as the context frame where the error occurred. However, InterSystems IRIS resets $ROLES to the value that was in effect for the execution level at which $ZTRAP was set; this prevents the $ZTRAP error handler from using elevated privileges that were granted to the routine after establishing the error handler. Upon completion of the $ZTRAP error handling routine, InterSystems IRIS unwinds the stack to the previous context level. This form of $ZTRAP is especially useful for analyzing unexpected errors.

Note that the asterisk sets a $ZTRAP option; it is not part of the location. For this reason, this asterisk does not display when performing a WRITE or ZZDUMP on $ZTRAP.

^%ETN

Location