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Version 2 (modified by todd.a, 8 years ago)

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Throw

The throw statement is used to signal the occurrence of an anomalous situation (exception) during the program execution.

The thrown exception is an object whose class is derived from System.Exception, for example:

class MyException inherits System.Exception
    pass
# ...
throw MyException()

Usually the throw statement is used with try-catch-finally statements.

You can also rethrow a caught exception using the throw statement by specifying the caught exception

catch exc as MyException
    if passOn
        throw exc  # rethrow caught exception
    # ...

Grammar

throw EXCEPTION_OBJECT

Example

class ThrowTest
    def getNumber(index as int) as int
        nums = [ 300, 600, 900 ]
        if index > nums.length
            throw IndexOutOfRangeException()
        return nums[index]

    def main is shared 
        result = ThrowTest.getNumber(3)

/#
    Output:
    The System.IndexOutOfRangeException exception occurs.
#/