Exceptions as Objects - Revision history

Manus at 12:17, 21 January 2016

2016-01-21T12:17:41Z

← Older revision		Revision as of 12:17, 21 January 2016
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	[[Category:Exception]]		[[Category:Exception]]
	[[Category:Language]]		[[Category:Eiffel Language]]
	== Overview ==		== Overview ==
	This article describes many aspects of Exceptions as Objects (ECMA-367 8.26) which will be implemented in ISE Eiffel. All exceptions will be raised as objects which can be accessed by `last_exception'. Exceptions as objects are known as type EXCEPTION and its descendants. EXCEPTION_MANAGER is introduced to handle common exception class operations, i.e. catch, and ignore.		This article describes many aspects of Exceptions as Objects (ECMA-367 8.26) which will be implemented in ISE Eiffel. All exceptions will be raised as objects which can be accessed by `last_exception'. Exceptions as objects are known as type EXCEPTION and its descendants. EXCEPTION_MANAGER is introduced to handle common exception class operations, i.e. catch, and ignore.

Manus at 12:16, 21 January 2016

2016-01-21T12:16:43Z

← Older revision		Revision as of 12:16, 21 January 2016
Line 1:		Line 1:
	[[Category:Exception]]		[[Category:Exception]]
			[[Category:Language]]
	== Overview ==		== Overview ==
	This article describes many aspects of Exceptions as Objects (ECMA-367 8.26) which will be implemented in ISE Eiffel. All exceptions will be raised as objects which can be accessed by `last_exception'. Exceptions as objects are known as type EXCEPTION and its descendants. EXCEPTION_MANAGER is introduced to handle common exception class operations, i.e. catch, and ignore.		This article describes many aspects of Exceptions as Objects (ECMA-367 8.26) which will be implemented in ISE Eiffel. All exceptions will be raised as objects which can be accessed by `last_exception'. Exceptions as objects are known as type EXCEPTION and its descendants. EXCEPTION_MANAGER is introduced to handle common exception class operations, i.e. catch, and ignore.

Conaclos: Syntax update 2

2014-07-02T21:59:03Z

Syntax update 2

← Older revision		Revision as of 21:59, 2 July 2014
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	class ANY		class ANY
	...		...
	default_rescue is		default_rescue
	do		do
	end		end

Conaclos: Style update

2014-07-02T21:58:13Z

Style update

← Older revision		Revision as of 21:58, 2 July 2014
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	== Sample code: Raising and catching developer exception ==		== Sample code: Raising and catching developer exception ==
	<eiffel>		<eiffel>
	class		class
	MY_EXCEPTION		MY_EXCEPTION

	inherit		inherit
	DEVELOPER_EXCEPTION		DEVELOPER_EXCEPTION

	end		end
	</eiffel>		</eiffel>
	<eiffel>		<eiffel>
	class		class
	A		A

	feature		feature

	f is		f
	local		local
	retried: BOOLEAN		retried: BOOLEAN
	do		do
	if not retried then		if not retried then
	my_exception.raise -- Raise user-defined exception.		my_exception.raise -- Raise user-defined exception.
	~~end~~
	~~rescue~~
	~~if last_exception = my_exception then -- Check the exception object was the one user defined.~~
	~~print ("True" + "%N")~~
	~~else~~
	~~print ("False" + "%N")~~
	~~end~~
	end		end
			rescue
			if last_exception = my_exception then -- Check the exception object was the one user defined.
			print ("True" + "%N")
			else
			print ("False" + "%N")
			end
			end

	my_exception: MY_EXCEPTION is		my_exception: MY_EXCEPTION
	once		once
	create Result		create Result
	end		end

	end		end
	</eiffel>		</eiffel>
	<eiffel>		<eiffel>
	class		class
	APPLICATION		APPLICATION

	inherit		inherit
	A		A

	create		create
	make		make

	feature -- Initialization		feature -- Initialization

	make is		make
	-- Run application.		-- Run application.
	local		local
	a: A		a: A
	retried: BOOLEAN		retried: BOOLEAN
	do		do
	if not retried then		if not retried then
	create a		create a
	a.f		a.f
	end		end
	rescue		rescue
	retried := True		retried := True

	-- `last_exception' is an object of ROUTINE_FAILURE?		-- `last_exception' is an object of ROUTINE_FAILURE?
	if attached {ROUTINE_FAILURE} (create {EXCEPTION_MANAGER}).last_exception as l_exception then		if attached {ROUTINE_FAILURE} (create {EXCEPTION_MANAGER}).last_exception as l_exception then
	print ("True" + "%N")		print ("True" + "%N")
	else		else
	print ("False" + "%N")		print ("False" + "%N")
	end		end

	-- `original' exception is the one caused `last_exception'?		-- `original' exception is the one caused `last_exception'?
	if last_exception.original = my_exception then		if last_exception.original = my_exception then
	print ("True" + "%N")		print ("True" + "%N")
	else		else
	print ("False" + "%N")		print ("False" + "%N")
	~~end~~
	~~retry~~
	end		end
			retry
			end

	end -- class APPLICATION		end -- class APPLICATION
	</eiffel>		</eiffel>

Conaclos: Update syntax

2014-07-02T21:47:36Z

Update syntax

← Older revision		Revision as of 21:47, 2 July 2014
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	local		local
	a: A		a: A
	~~l_exception: ROUTINE_FAILURE~~
	retried: BOOLEAN		retried: BOOLEAN
	do		do
Line 364:		Line 363:
	rescue		rescue
	retried := True		retried := True
	~~l_exception ?= (create {EXCEPTION_MANAGER}).last_exception~~ -- ~~Check~~ `last_exception' is an object of ROUTINE_FAILURE
	if l_exception ~~/= Void~~ then		-- `last_exception' is an object of ROUTINE_FAILURE?
			if attached {ROUTINE_FAILURE} (create {EXCEPTION_MANAGER}).last_exception as l_exception then
	print ("True" + "%N")		print ("True" + "%N")
	else		else
	print ("False" + "%N")		print ("False" + "%N")
	end		end
	~~if last_exception.original = my_exception then~~ -- `original' exception is the one caused `last_exception'
			-- `original' exception is the one caused `last_exception'?
			if last_exception.original = my_exception then
	print ("True" + "%N")		print ("True" + "%N")
	else		else

Ted: /* Exception at rescue clause */

2009-03-26T06:24:10Z

Exception at rescue clause

← Older revision		Revision as of 06:24, 26 March 2009
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	[[Image:exception_in_rescue.png]]		[[Image:exception_in_rescue.png]]

	Exception e2 is ~~thrown away~~ at c.~~f3, instruction of rescue clause,~~ in which e3 is raised. In this case ~~we only keep~~ e3 ~~in the stack~~ and accessible by `~~last_exception~~'.		Exception e2 is kept as `cause' at d.f4 in which e3 is raised, and being called in rescue clause r2. In this case e3 is accessible by `last_exception' and e2 is accessible by `cause' of e3.
	<br>		<br>
	<br>		<br>

Ted: /* Class EXCEPTION */

2009-03-09T01:27:58Z

Class EXCEPTION

← Older revision		Revision as of 01:27, 9 March 2009
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	-- Code of the exception.		-- Code of the exception.
	-- \|Maybe we don't need this anymore		-- \|Maybe we don't need this anymore

	~~data: ANY~~
	~~-- Data set by user~~

	exception_trace: STRING_8		exception_trace: STRING_8
Line 191:		Line 188:
	original: EXCEPTION		original: EXCEPTION
	-- Original exception that triggered current exception		-- Original exception that triggered current exception

			cause: EXCEPTION
			-- Unhandled exception before current exception was triggered in a rescue clause

	recipient_name: STRING_8		recipient_name: STRING_8
Line 226:		Line 226:
	require		require
	is_raisable: is_raisable		is_raisable: is_raisable

	~~feature -- Status settings~~

	~~set_data (a_data: like data)~~
	~~-- Set data with `a_data'.~~
	~~ensure~~
	~~data_is_set: data = a_data~~

	end -- class EXCEPTION		end -- class EXCEPTION

Ted: Added new section `origin' VS `cause'.

2009-03-09T01:22:18Z

Added new section `origin' VS `cause'.

← Older revision		Revision as of 01:22, 9 March 2009
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	set_is_ignored (a_exception: TYPE [EXCEPTION]; a_ignored: BOOLEAN)		set_is_ignored (a_exception: TYPE [EXCEPTION]; a_ignored: BOOLEAN)
	</eiffel>		</eiffel>

			== `origin' VS `cause' ==

			* The origin of an exception is, among all exceptions that have so far been triggered but not handled, the most recent one that is not a ROUTINE_FAILURE. Because a ROUTINE_FAILURE is always the result of an exception of another kind, the `origin' is always defined.

			* The `cause' of an exception is only interesting in the case of an exception triggered in a rescue clause. In that case the exception is the result of incomplete handling of another exception (which might be a ROUTINE_FAILURE or any other kind). Then the `cause' is that other exception.

			* If an exception was not triggered in a rescue clause, its `cause' is the exception itself.

	== Exception at rescue clause ==		== Exception at rescue clause ==

Ted: Cosmetics

2009-03-09T01:12:21Z

Cosmetics

← Older revision		Revision as of 01:12, 9 March 2009
Line 86:		Line 86:

	<eiffel>		<eiffel>
	is_ignored: BOOLEAN		is_ignored: BOOLEAN
	is_caught: BOOLEAN		is_caught: BOOLEAN
	is_ignorable: BOOLEAN		is_ignorable: BOOLEAN
	</eiffel>		</eiffel>

Line 94:		Line 94:

	<eiffel>		<eiffel>
	is_caught (a_exception: TYPE [EXCEPTION]): BOOLEAN		is_caught (a_exception: TYPE [EXCEPTION]): BOOLEAN
	is_ignored (a_exception: TYPE [EXCEPTION]): BOOLEAN		is_ignored (a_exception: TYPE [EXCEPTION]): BOOLEAN
	is_ignorable (a_exception: TYPE [EXCEPTION]): BOOLEAN		is_ignorable (a_exception: TYPE [EXCEPTION]): BOOLEAN
	catch (a_exception: TYPE [EXCEPTION])		catch (a_exception: TYPE [EXCEPTION])
	ignore (a_exception: TYPE [EXCEPTION])		ignore (a_exception: TYPE [EXCEPTION])
	set_is_ignored (a_exception: TYPE [EXCEPTION]; a_ignored: BOOLEAN)		set_is_ignored (a_exception: TYPE [EXCEPTION]; a_ignored: BOOLEAN)
	</eiffel>		</eiffel>

Manus: /* Exception at rescue clause */

2007-10-08T17:42:19Z

Exception at rescue clause

← Older revision		Revision as of 17:42, 8 October 2007
Line 111:		Line 111:
	<br>		<br>
	<b>		<b>
	An behavior should be clarified, that when an exception occurs deep in execution level of a rescue clause, `last_exception' is understood as "last unhandled exception".		A behavior should be clarified, that when an exception occurs deep in execution level of a rescue clause, `last_exception' is understood as "last unhandled exception".
	</b>		</b>
	<br>		<br>