break

Owned by Former user (Deleted)
Last updated: Sept 23, 2021 by Anthony George
2 min read



Function: break()

Within a do() or forEach() function, break() causes the do() or forEach() functions to stop immediately and return a _NULL value. $-variables in the environment of the forEach() or do() that were in scope directly before break() was called will still be available after the call to break(). 

If used outside of a do() or forEach() function then break() will cause the analysis for the Stream Set to stop as though a stop() function was called (but will produce an error message rather than a warning message). No records will be saved for that Stream Set.

If used inside of a do() or forEach() function that is itself nested inside of another do() or forEach() function, break() will only exit the inner (nested) function call. The outer expression will continue to be evaluated in the usual way.

Syntax

break()

Examples

In this first example, forEach() is used to iterate over a list of manager names until "Wally" is found, at which point we can stop looking. Used in a string-valued field on a stream, this would output the value "Found Wally!" into the stream record in that field.

Note how $outputString is still available after the call to break() has been made and the do() routine has terminated.


do(
   $outputString = "Can't find Wally..."
   
   forEach($manager, $managersList
   	  
	  if($manager = "Wally",
   	     do(
			$outputString "Found Wally!"
			break()
		 )
   	  )
   ),
   
   //output the result
   $outputString
)


The above example (somewhat contrived, see included() or subset() for a more practical solution) shows how break() can be useful when iterating over lists, if you don't need knowledge of all of the elements.


In this next example, the forEach() function will check each prefix in turn until it finds a prefix length greater than 20 at which point a debug message will be printed out to the log and break() will be called which causes the loop to stop processing.

forEach( $prefix, lookup.prefixes, 

   if( stringLength($prefix) > 20, 
      do ( 
         debug("Stopping because prefix > 20"), 
         break() 
      ) 
   ), 

   $highest = $prefix 
)


Note that the call to break() exits both the inner do() routine, and the outer forEach() - but not the current stream processing cycle.

See Also