The optional raises expression ("raises-expr") in a method declaration indicates which exceptions the method may raise. (IDL exceptions are implemented by simply passing back error information after a method call, as opposed to the "catch/throw" model where an exception is implemented by a long jump or signal.) A raises expression is specified as follows:
raises ( identifier1, identifier2,... )
where each "identifier" is the name of a previously defined exception. In addition to the exceptions listed in the raises expression, a method may also signal any of the standard exceptions. Standard exceptions, however, should not appear in a raises expression. If no raises expression is given, then a method can raise only the standard exceptions. (See the earlier topic "Exception declarations" for information on defining exceptions and for the list of standard exceptions. See Chapter 3, the section entitled "Exceptions and error handling," for information on using exceptions.)