EiffelBase2 - Revision history

Kenga: /* Iterators */

2014-04-30T11:04:53Z

Iterators

← Older revision		Revision as of 11:04, 30 April 2014
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	container as i		container as i
	loop		loop
	print (i.item)		print (i.item)
	~~i.forth~~
	end		end
	end		end

Kenga: /* Status and roadmap */

2012-06-27T13:22:34Z

Status and roadmap

← Older revision		Revision as of 13:22, 27 June 2012
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	It has been used in the following projects:		It has been used in the following projects:
	* Traffic 4: modeling public transportation in a city [~~http~~://~~traffic~~.~~origo.ethz.ch~~/ ~~http~~://~~traffic~~.~~origo.ethz.ch~~/]		* Traffic 4: modeling public transportation in a city [https://bitbucket.org/nadiapolikarpova/traffic https://bitbucket.org/nadiapolikarpova/traffic]

Kenga: /* Sets and tables */

2012-04-11T14:19:29Z

Sets and tables

← Older revision		Revision as of 14:19, 11 April 2012
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	-- Drive `c' away, repaint it and update its view.		-- Drive `c' away, repaint it and update its view.
	require		require
	~~car_on_map~~: cars.has_key (c)		car_in_city: cars.has_key (c)
	do		do
	c.move (100, 100) -- change location		c.move (100, 100) -- change location

Kenga: /* Sets and tables */

2012-04-11T14:18:59Z

Sets and tables

← Older revision		Revision as of 14:18, 11 April 2012
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	feature		feature
	cars: V_HASH_TABLE [CAR, CAR_VIEW]		cars: V_HASH_TABLE [CAR, CAR_VIEW]
			-- Cars in the city and their graphical views.

	escape_police (c: CAR)		escape_police (c: CAR)
			-- Drive `c' away, repaint it and update its view.
	require		require
	car_on_map: cars.has_key (c)		car_on_map: cars.has_key (c)

Kenga: /* Sets and tables */

2012-04-11T14:16:49Z

Sets and tables

← Older revision		Revision as of 14:16, 11 April 2012
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	class ~~MAP~~		class GUI_APPLICATION

	feature		feature

Kenga: /* Sets and tables */

2012-04-11T14:14:25Z

Sets and tables

← Older revision		Revision as of 14:14, 11 April 2012
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	Sometimes you want to use an object as a key in a table,		Sometimes you want to use an object as a key in a table,
	but the content of the object can change, so you cannot derive a hash code (or order) from any of its attributes.		but the content of the object can change, so you cannot derive a hash code (or order) from any of its attributes.
	EiffelBase2 provides a utility class <e>~~V_REFERNCE_HASHABLE~~</e>,		EiffelBase2 provides a utility class <e>V_REFERENCE_HASHABLE</e>,
	which derives a hash code from the object's identity rather than its content.		which derives a hash code from the object's identity rather than its content.
	For example:		For example:

Kenga: /* Sets and tables */

2012-04-11T13:34:40Z

Sets and tables

← Older revision		Revision as of 13:34, 11 April 2012
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	Similar style applies to <e>V_HASH_SET</e> and <e>V_GENERAL_HASH_SET</e>, <e>V_SORTED_TABLE</e> and <e>V_GENERAL_SORTED_TABLE</e>, <e>V_SORTED_SET</e> and <e>V_GENERAL_SORTED_SET</e>.		Similar style applies to <e>V_HASH_SET</e> and <e>V_GENERAL_HASH_SET</e>, <e>V_SORTED_TABLE</e> and <e>V_GENERAL_SORTED_TABLE</e>, <e>V_SORTED_SET</e> and <e>V_GENERAL_SORTED_SET</e>.

			Sometimes you want to use an object as a key in a table,
			but the content of the object can change, so you cannot derive a hash code (or order) from any of its attributes.
			EiffelBase2 provides a utility class <e>V_REFERNCE_HASHABLE</e>,
			which derives a hash code from the object's identity rather than its content.
			For example:
			<e>
			class
			CAR
			inherit
			V_REFERENCE_HASHABLE

			feature -- Access
			color: COLOR

			location: POINT

			feature -- Modification
			...
			end


			class MAP

			feature
			cars: V_HASH_TABLE [CAR, CAR_VIEW]

			escape_police (c: CAR)
			require
			car_on_map: cars.has_key (c)
			do
			c.move (100, 100) -- change location
			c.repaint (white) -- change color
			cars [c].update -- ... but still can be used to access its view
			end
			end
			</e>

	===Stream piping===		===Stream piping===

Kenga: /* Inheritance */

2012-04-05T15:33:31Z

Inheritance

← Older revision		Revision as of 15:33, 5 April 2012
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	If a class <e>B</e> inherits from <e>A</e> it is free to choose, whether to reuse each of <e>A</e>'s model queries to represent its own model, as well as introduce new model queries. If <e>B</e> does not reuse an <e>A</e>'s model query is has to provide a ''linking invariant'': a definition of the old model query in terms of <e>B</e>'s model. Linking invariants explain the parent's model in terms of the heir's model and thus make sure that the inherited model-based contracts make sense in the heir.		If a class <e>B</e> inherits from <e>A</e> it is free to choose, whether to reuse each of <e>A</e>'s model queries to represent its own model, as well as introduce new model queries. If <e>B</e> does not reuse an <e>A</e>'s model query is has to provide a ''linking invariant'': a definition of the old model query in terms of <e>B</e>'s model. Linking invariants explain the parent's model in terms of the heir's model and thus make sure that the inherited model-based contracts make sense in the heir.

	For example, ~~suppose that~~ <e>~~LIST~~</e> inherits directly from <e>~~CONTAINER~~</e>~~, whose model is a bag~~:		For example, look at <e>V_SET</e>, which inherits directly from <e>V_CONTAINER</e>:
	<e>		<e>
	note		note
	model: bag		model: bag
	class ~~CONTAINER~~ [G]		class V_CONTAINER [G]
	...		...
	end		end

	note		note
	model: ~~sequence, index~~		model: set
	class ~~LIST~~ [G]		class V_SET[G]
	...		...
	invariant		invariant
	...		...
	bag_domain_definition: bag.domain = ~~sequence.range~~		bag_domain_definition: bag.domain \|=\| set
	bag_definition: bag.~~domain.for all (agent (x: G): BOOLEAN~~		bag_definition: bag.is_constant (1)
	~~do Result := bag [x] = sequence.occurrences~~ (~~x) end~~)
	end		end
	</e>		</e>
	Here the linking invariant, provided as part of the class invariant in <e>~~LIST~~</e> completely defines an old model query <e>bag</e> in terms of a new model query <e>~~sequence~~</e>.		Here the linking invariant, provided as part of the class invariant in <e>V_SET</e> completely defines an old model query <e>bag</e> in terms of a new model query <e>set</e>.

	==Status and roadmap==		==Status and roadmap==

Kenga: /* Status and roadmap */

2012-04-05T15:29:03Z

Status and roadmap

← Older revision		Revision as of 15:29, 5 April 2012
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	EiffelBase2 is currently being developed as a project at ETH Zurich.		EiffelBase2 is currently being developed as a project at ETH Zurich.

	It has been used in the following projects:		It has been used in the following projects:
	* Traffic 4: modeling public transportation in a city [http://traffic.origo.ethz.ch/ http://traffic.origo.ethz.ch/]		* Traffic 4: modeling public transportation in a city [http://traffic.origo.ethz.ch/ http://traffic.origo.ethz.ch/]

Kenga: /* Models */

2012-04-05T15:27:38Z

Models

← Older revision		Revision as of 15:27, 5 April 2012
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	note		note
	model: target, sequence, index		model: target, sequence, index
	class ~~V_ITERATOR~~ [G]
			class V_LIST_ITERATOR [G]

	feature -- Access		feature -- Access

	target: ~~V_CONTAINER~~		target: V_LIST
	-- ~~Container~~ to iterate over.		-- List to iterate over.
	deferred		deferred
	end		end
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	end		end
	</e>		</e>
	Here we declared the model of class <e>~~V_ITERATOR~~</e> consisting of tree components:
	a reference (to <e>~~V_CONTAINER~~</e>), a mathematical sequence of type <e>MML_SEQUENCE</e> and an integer index.		Here we declared the model of class <e>V_LIST_ITERATOR</e> consisting of tree components:
			a reference (to <e>V_LIST</e>), a mathematical sequence of type <e>MML_SEQUENCE</e> and an integer index.
	As you can see, model queries are not necessarily introduced specifically for specification purposes (as is the case with <e>sequence</e>);		As you can see, model queries are not necessarily introduced specifically for specification purposes (as is the case with <e>sequence</e>);
	regular queries meant to be called from the code can be also reused as model queries (as <e>target</e> and <e>index</e> in this example).		regular queries meant to be called from the code can be also reused as model queries (as <e>target</e> and <e>index</e> in this example).