2007-06-12 10:39:47 +00:00
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================================================================
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Logtalk - Open source object-oriented logic programming language
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2007-11-06 01:50:09 +00:00
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Release 2.30.7
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2002-05-28 11:35:10 +00:00
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2007-01-10 12:46:10 +00:00
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Copyright (c) 1998-2007 Paulo Moura. All Rights Reserved.
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2007-06-12 10:39:47 +00:00
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================================================================
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2002-05-28 11:35:10 +00:00
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2004-06-13 18:04:28 +00:00
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% start by loading the example:
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2004-11-29 20:36:31 +00:00
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| ?- logtalk_load(dynpred(loader)).
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2004-06-13 18:04:28 +00:00
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...
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% sending to descendant the message p/1, returns the definition in root:
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2002-05-28 11:35:10 +00:00
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| ?- descendant::p(Value).
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Value = root
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yes
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2004-06-13 18:04:28 +00:00
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% asserting a local definition for p/1 in descendant overrides the inherited
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2002-05-28 11:35:10 +00:00
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% definition:
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| ?- descendant::(assertz(p(descendant)), p(Value)).
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Value = descendant
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yes
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2005-04-22 23:57:45 +00:00
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% if we retract the local definition, again the definition inherited from root
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2002-05-28 11:35:10 +00:00
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% will be used:
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| ?- descendant::(retractall(p(_)), p(Value)).
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Value = root
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yes
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% class does not understand the message p1/1 (the predicate is declared only
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% for the class descendant instances):
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| ?- class::p1(X).
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error(existence_error(predicate_declaration, p1(_)), class::p1(_), user)
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% the same message is valid for the class instances:
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| ?- instance::p1(X).
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X = class
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yes
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2004-06-13 18:04:28 +00:00
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% if we assert a clause for a new predicate, p2/1, in the class
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2002-05-28 11:35:10 +00:00
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% (a side-effect being a dynamic declaration of the predicate):
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| ?- class::assertz(p2(class)).
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yes
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% the new predicate, like p1/1, is not available for the class:
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| ?- class::p2(Value).
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error(existence_error(predicate_declaration, p2(_)), class::p2(_), user)
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% but is available for the class instances, the same way as p1/1:
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| ?- instance::p2(X).
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X = class
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yes
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2004-06-13 18:04:28 +00:00
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% using a prototype, assert three new predicates (the method object_assert/0
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2002-05-28 11:35:10 +00:00
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% asserts the predicate public_predicate/0 from outside the prototype; the
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% method self_assert/0 asserts the predicate protected_predicate/0 in self;
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% the method this_assert/0 asserts the predicate private_predicate/0 in this):
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| ?- prototype::(object_assert, self_assert, this_assert).
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yes
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% and check the resulting scope of each predicate:
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| ?- prototype::dynamic_predicates.
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public_predicate/0 - public
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protected_predicate/0 - protected
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private_predicate/0 - private
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yes
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