Example 5: WHENEVER RAISE expection propagation

This example shows the usage of WHENEVER ... RAISE to propagate a potential exception to the caller. First the program defines the foo function as exception handler with WHENEVER ANY ERROR CALL foo, then it calls the do_exception function, which instructs the runtime system to propagate a potential error to the caller. As result, the division by zero in line #13 will be caught by the error handler defined in the MAIN block and call the foo function:

MAIN
    DEFINE i INTEGER
    WHENEVER ANY ERROR CALL foo 
    DISPLAY "Next function call will generate an exception"
    DISPLAY do_exception(100, 0)
    WHENEVER ANY ERROR STOP -- reset default handler for rest of program 
    ...
END MAIN

FUNCTION do_exception(a, b)
    DEFINE a, b INTEGER
    WHENEVER ANY ERROR RAISE
    RETURN a / b 
END FUNCTION

FUNCTION foo()
    DISPLAY "Exception caught, status: ", STATUS
END FUNCTION

Program output:

Next function call will generate an exception 
Exception caught, status:    -1202