Example 4: TRY / CATCH in conjunction with WHENEVER

This code illustrates the fact that a TRY/CATCH block can be used together with a WHENEVER instruction: The program first executes a WHENEVER ANY ERROR to define an error handler named foo and later it uses a TRY/CATCH block to trap expression errors.

In this example, we intentionally force a division by zero. After the TRY/CATCH block, we force another division by zero error, which will call the foo error handler:

MAIN
  DEFINE i INTEGER
  WHENEVER ANY ERROR CALL foo
  TRY
    DISPLAY "Next exception should be handled by the catch statement"
    LET i = i / 0
  CATCH
    DISPLAY "Exception caught, status: ", status
  END TRY
  -- Previous error handler is restored after the TRY - CATCH block 
  LET status = 0
  DISPLAY "Next exception should be handled by the foo function"
  LET i = i / 0
END MAIN

FUNCTION foo() RETURNS ()
  DISPLAY "Function foo called, status: ", status
END FUNCTION

Program output:

Next exception should be handled by the catch statement
Exception caught, status:      -1202
Next exception should be handled by the foo function 
Function foo called, status:      -1202