Caché ObjectScript Reference - InterSystems Documentation

You then use the SET command to assign a different value to the new copy of $ETRAP. Inthis way, you can establish new $ETRAP error-handling commands for the current context.You can also clear $ETRAP by setting it to the null string. Caché then executes no $ETRAPcommands at the context level in the event of an error.When a QUIT command causes the current context to be exited, Caché restores the old, savedvalue of $ETRAP.ExampleThe following example demonstrates how the value of $ETRAP is carried forward into newcontexts and how you can invoke $ETRAP error-handling commands again in each contextafter an error occurs. The $ETRAP commands in this example make no attempt to dismissthe error. Rather, control by default is passed back to $ETRAP error-handling commands ateach previous context level.The sample code is as follows:ETRNEW $ETRAPSET $ETRAP="WRITE !,""$ETRAP invoked at Context Level "",$STACK"; Initiate an XECUTE context that initiates a DO contextXECUTE "DO A"QUIT; Initiate a user-defined function contextASET A=$$BQUIT; A User-defined function that generates an errorB()QUIT 1A sample session using this code might run as follows:>DO ^ETR$ETRAP invoked at context level 4$ETRAP invoked at context level 3$ETRAP invoked at context level 2$ETRAP invoked at context level 1NotesUse NEW Before Setting $ETRAP to a New Value$ETRAPIf you assign a new value to $ETRAP in a context without first creating a new copy of$ETRAP with the NEW command, Caché establishes that new value as the value of $ETRAPnot only for the current context but also for all previous contexts. Therefore, InterSystemsstrongly recommends that you create a new copy of $ETRAP with the NEW commandbefore it is set with a new value.Caché ObjectScript Reference 427