46c8cfbeff
git-svn-id: https://yap.svn.sf.net/svnroot/yap/trunk@1799 b08c6af1-5177-4d33-ba66-4b1c6b8b522a
34 lines
1.4 KiB
Plaintext
34 lines
1.4 KiB
Plaintext
=================================================================
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Logtalk - Object oriented extension to Prolog
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Release 2.29.4
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Copyright (c) 1998-2007 Paulo Moura. All Rights Reserved.
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=================================================================
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To load this example and for sample queries, please see the SCRIPT file.
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A parametric object may be used to represent objects whose "state" is static
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and set when the object is defined. However, there can be only one parametric
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object with a given functor and arity. For example, if we define the following
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parametric object:
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:- object(circle(_Radius, _Color)).
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...
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:- end_object.
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then the following terms may be interpreted as references to the object above:
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circle(1, blue)
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circle(2, yellow)
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In the context of parametric objects, the above terms are know as "parametric
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object proxies". Proxies represent different instantiations of a parametric
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object parameters. They may be stored on the database as Prolog facts. This
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results in a very compact representation, which can be an advantage when
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dealing with a large number of objects with immutable state. However, this is
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also a fragile solution as changes on the parametric object ancestors may
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imply changes to the number and meaning of the parametric object parameters
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which, in turn, may imply changes to all the Prolog facts used to represent
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the individual objects.
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