Caché ObjectScript Reference - InterSystems Documentation

Caché ObjectScript Special Variables$ETRAPContains a string of Caché ObjectScript commands to be executed when an error occurs.$ETRAP$ETDescription$ETRAP contains a string that specifies one or more Caché ObjectScript commands that areexecuted when an error occurs.You use the SET command to give $ETRAP the value of a string that contains one or moreCaché ObjectScript commands. Then, when an error occurs, Caché executes the commandsyou entered into $ETRAP. For example, suppose you set $ETRAP to a string that containsa GOTO command to transfer control to an error-handling routine:SET $ETRAP="GOTO LOGERR^ERRROU"Caché then executes this command in $ETRAP immediately following any Caché ObjectScriptcommand that generates an error condition. Caché executes the $ETRAP command(s) at thesame context level in which the error condition occurs.$ETRAP Commands Compared with XECUTE CommandsThe commands in a $ETRAP string are not executed in a new context level, unlike thecommands in an XECUTE string. In addition, the $ETRAP command string is always terminatedby an implicit QUIT command. The implicit QUIT command quits with a null-stringargument when the $ETRAP error-handling commands are invoked in a user-defined functioncontext where an argumented QUIT command is required.Setting $ETRAP Values in Different Context LevelsBy default, Caché carries the value of the $ETRAP special variable forward into new DO,XECUTE, and user-defined function contexts. However, you can create a new copy of$ETRAP in a context by issuing the NEW command, as follows:NEW $ETRAPWhenever you issue a NEW for $ETRAP, Caché performs the following actions:1. Saves the copy of $ETRAP that was in use at that point.2. Creates a new copy of $ETRAP.3. Assigns the new copy of $ETRAP the same value as the old, saved copy of $ETRAP.426 Caché ObjectScript Reference