Object Layout - Revision history

Manus at 10:13, 11 April 2007

2007-04-11T10:13:34Z

2007-04-11T10:13:23Z

2007-01-10T14:04:43Z

‎An example

2007-01-09T21:29:38Z

2007-01-09T21:29:13Z

2007-01-09T16:25:19Z

2007-01-09T14:46:57Z

‎An example

2007-01-09T14:18:31Z

‎An example

2007-01-09T14:18:22Z

‎The layout

2007-01-09T14:18:13Z

‎An example

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 [[Category:Compiler]]
-{UnderConstruction}}
+{{UnderConstruction}}
 This page gives a short overview to the runtime object layout for Eiffel Systems compiled with Eiffel Studio.

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 [[Category:Compiler]]
-{{Warning|'''Warning''': Article under development}}
+{UnderConstruction}}
 This page gives a short overview to the runtime object layout for Eiffel Systems compiled with Eiffel Studio.

← Older revision		Revision as of 14:04, 10 January 2007
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	Attribute a1 has a different relative position in memory for objects of class A or B. So when accessing a1 of an object the exact type of the object needs to be known.		Attribute a1 has a different relative position in memory for objects of class A or B. So when accessing a1 of an object the exact type of the object needs to be known.
−	~~[[Media:Example.ogg]]~~

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 {{Warning|'''Warning''': Article under development}}
 This page gives a short overview to the runtime object layout for Eiffel Systems compiled with Eiffel Studio.
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 Attribute a1 has a different relative position in memory for objects of class A or B. So when accessing a1 of an object the exact type of the object needs to be known.

← Older revision		Revision as of 21:29, 9 January 2007
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		+	{{Warning\|'''Warning''': Article under development}}
	This page gives a short overview to the runtime object layout for Eiffel Systems compiled with Eiffel Studio.		This page gives a short overview to the runtime object layout for Eiffel Systems compiled with Eiffel Studio.

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 ====Requirements====
-An object in memory needs to hold different informations. First of all the current values of its attributes and the dynamic type id of the object. Besides that, the garbage collection needs some additional information saved per object.
+An object in memory needs to hold different information. First of all the current values of its attributes and the dynamic type id of the object. Besides that, the garbage collection needs some additional information saved per object.
 The object layout has to provide both fast access to the attributes and the garbage collector (gc) with a way to explore all the reference fields of an object. The latter is important during the marking phase of the gc.

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 ====An example====
 The following picture shows the effective memory layout for an EiffelSystem composed of classes A and B:
 [[Image:EiffelStudioObjectLayoutExample.jpg]]

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 ====The layout====
 The following picture shows the principal object layout chosen for EiffelStudio:
 [[Image:EiffelStudioObjectLayout.jpg]]
 The picture shows, that a reference to an object points to the first attribute of the object. The object actually starts earlier. The part of the object that comes prior to the fields is called the overhead. The overhead contains the type id of the object and some additional information for the garbage collector.