CLIPS:修改实例不触发模式匹配 [英] CLIPS: modify-instance does not trigger pattern matching
问题描述
有一个文件 test.clp:
Having a file test.clp:
(defclass TestClass (is-a USER)
(role concrete)
(pattern-match reactive)
(slot value)
(slot threshold))
(definstances TestObjects
(Test of TestClass
(value 0)
(threshold 3)))
(defrule above-threshold
?test <- (object (is-a TestClass))
(test (> (send ?test get-value) (send ?test get-threshold)))
=>
(printout t "*** Above threshold!! ***" crlf)
(refresh below-threshold))
(defrule below-threshold
?test <- (object (is-a TestClass))
(test (> (send ?test get-value) (send ?test get-threshold)))
=>
(printout t "*** Back to normal ***" crlf)
(refresh above-threshold))
我加载文件并:
CLIPS> (reset)
CLIPS> (agenda)
0 below-threshold: [Test]
For a total of 1 activation.
CLIPS> (run)
*** Back to normal ***
CLIPS> (modify-instance [Test] (value 8))
TRUE
CLIPS> (agenda)
CLIPS>
议程没有显示任何活动规则.我希望将值(修改实例)更改为 8 会触发模式匹配,并且会选择规则高于阈值"来运行并放入议程.我错过了什么?
The agenda does not show any active rule. I would expect the change (modify-instance) for value to 8 would trigger pattern matching and rule "above-threshold" would be selected for running and put in the agenda. What am I missing?
推荐答案
来自《基本编程指南》的第 5.4.1.7 节,与对象模式的模式匹配:
From section 5.4.1.7, Pattern-Matching with Object Patterns, of the Basic Programming Guide:
创建或删除实例时,所有模式适用于该对象已更新.但是,当插槽更改时,只有那些在该插槽上明确匹配的模式会受到影响.
When an instance is created or deleted, all patterns applicable to that object are updated. However, when a slot is changed, only those patterns that explicitly match on that slot are affected.
因此修改规则以明确匹配您要触发模式匹配的插槽:
So modify the rules to explicitly match the slots you want to trigger pattern matching:
(defrule above-threshold
?test <- (object (is-a TestClass)
(value ?value)
(threshold ?threshold))
(test (> ?value ?threshold))
=>
(printout t "*** Above threshold!! ***" crlf)
(refresh below-threshold))
(defrule below-threshold
?test <- (object (is-a TestClass)
(value ?value)
(threshold ?threshold))
(test (< ?value ?threshold))
=>
(printout t "*** Back to normal ***" crlf)
(refresh above-threshold))
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