Possible Exception Hierarchies

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Possible Exception Hierarchies

Below are three exception hierarchies: the current 4thEstate base system, my [STP] proposed extensions, and a more complete example taken from the VisualWorks Non-Commercial system (with some platform-specific ones removed).
Current "out of the box" TFEI Exceptions



	Exception ('messageText' 'initialContext' 'resignalException' 'handlerContext' 'tag' )

		BlockCannotReturn ('result' )

		Error ()

			Halt ()

			MessageNotUnderstood ('message' )

			MyResumableTestError ()

			MyTestError ()

			ZeroDivide ('dividend' )

		IllegalResumeAttempt ()

		Notification ()

			ExceptionAboutToReturn ()

			MyTestNotification ()

			Warning ()



Proposed Squeak Exception Hierarchy (based on TFEI and VWNC)



	Exception ('messageText' 'initialContext' 'resignalException' 'handlerContext' 'tag' )

		BlockCannotReturn ('result' )

		Error ()

			Halt ()

			UserInterrupt ()

			MessageNotUnderstood ('message' )

			ArithmeticError ()

				DomainError ()

					ZeroDivide ()

					SqrtOfNegativeError()

					LogOfZeroError()

				RangeError ()

					UnderflowError ()

					OverflowError ()

			AccessingError()

				CollectionAccessingError ()

					NotOrderedError ()

			FileError()

				IllegalFilenameError ()

				DirectoryNotFoundError ()

				FileProtectionError ()

				VolumeFullError ()

			NotFoundError ()

				IndexNotFoundError ()

					BindingNotFoundError ()

					KeyNotFoundError ()

					NonIntegerIndexError ()

					SubscriptOutOfBoundsError ()

					ValueNotFoundError ()

			PrimitiveFailure ()

			SignalError ()

			SnapshotError ()

			StreamError ()

				StreamAtEndError ()

				StreamWriteError ()

				PositionOutOfBoundsError ()

			SubclassResponsibilityError ()

			ShouldNotImplementError ()

		IllegalResumeAttempt ()

		Notification ()

			ExceptionAboutToReturn ()

			FinalizeCallbackProcessNotification ()

			Warning ()



VWNC3 Exceptions (somewhat simplified, for reference)



	GenericException ('messageText' 'originator' 'initialContext' 'firstUnwindContext' 'handlerContext' 'parameter' 'isResumable' 'signal')

		ControlInterrupt ()

			HaltInterrupt ()

			SystemNotification ()

			UserInterrupt ()

		Exception ()

			ContextEmergencyError ()

			Error ()

				AllocationFailure ()

				ArithmeticError ()

					DomainError ()

						ZeroDivide ()

					RangeError ()

					UnorderedNumbersError ()

				BadControllerError ()

				CannotResumeError ()

				CannotReturnError ()

				CantReopenError ()

				ClassConstructionError ()

				CodeSimulationError ()

				CodeStorageError ()

				ColorError ()

				CompilationError ()

				CTypeError ()

				ExceededLimitsError ()

				ExternalAccessFailed ()

				ExternalLibraryError ()

					ExternalObjectNotFoundError ()

					LibraryNotFoundError ()

					LibraryNotLoadedError ()

					LibraryNotUnloadedError ()

				InterruptLockedError ()

				InvalidFormatError ()

				InvalidNumberOfArgumentsError ()

				MemberNotFoundError ()

				MessageNotUnderstood ()

				NonCharacterError ()

				NotFoundError ()

					IndexNotFoundError ()

						BindingNotFoundError ()

						KeyNotFoundError ()

						NonIntegerIndexError ()

						SubscriptOutOfBoundsError ()

						ValueNotFoundError ()

				ObsoleteClassError ()

				OsError ()

					OsIllegalOperation ()

					OsInaccessibleError ()

					OsInvalidArgumentsError ()

					OsNeedRetryError ()

					OsNoResourcesError ()

					OsNotification ()

					OsTransferFaultError ()

				PrimitiveFailure ()

				QueueOverflowError ()

				RestartRequest ()

				SignalError ()

				SnapshotError ()

				StreamError ()

					IncompleteNextCountError ()

					PositionOutOfBoundsError ()

				SubclassResponsibilityError ()

				UnsupportedCharacterError ()

			InformationSignal ()

				AccessActiveProcessNotification ()

			Notification ()

				ClosedWindowNotification ()

				CommentRequestNotification ()

				DoubleClickNotification ()

				EndOfStreamNotification ()

				FinalizeCallbackProcessNotification ()

				GetBaseContextForException ()

				NoOptimizeNotification ()

				VariableReadBeforeWrittenNotification ()

				VetoAction ()

			UserNotification ()

			Warning ()

		PromiseTerminateException ()

		TerminateException ()

		UnhandledException ()