CLIPS instance <> and []? Instance eq to itself FALSE?

Question

I have an ontology where I define two classes this way:

(defclass A
    (is-a USER)
    (role concrete)
    (single-slot TheB
            (type INSTANCE)
            (allowed-classes B)
            (create-accessor read-write)))
(defclass B
    (is-a USER)
    (role concrete)
    (single-slot Id
        (type STRING)
        (create-accessor read-write)))

So I create an instance of B [b] and another of A [a] referencing [b]. Then I have the following rule:

(defrule myrule
    ?b <- (object (is-a B))
    ?a <- (object (is-a A)
                    (TheB ?y&:(= (str-compare (send ?b get-Id) (send ?y get-Id)) 0)))
    =>
    (printout t ?y " " ?b crlf)
    (printout t (type ?y) " " (type ?b) crlf)
    (printout t (eq ?y ?b) crlf)
    (printout t ?a "->" (send ?a get-TheB) crlf)
)

When I run I obtain the following output:

[b] <Instance-b>
B B
FALSE
<Instance-a>->[b]

Can someone explain me what is the difference between one and another? Why one has "<>" and the other "[]" but the type is the same? Do I have to compare the id's necessarily? There is no way I can obtain the <> from the []?

Thank you very much for your attention.

Answer 1

您可以通过名称（字符串）或地址（指向实例的指针）来引用实例。将消息发送到实例地址比将消息发送到实例名称要快一些，因为没有涉及将名称转换为地址的查找。无论使用名称还是地址来确定有效实例的类型，结果都是相同的（实例的类）。在您的示例中，[b]是实例的名称，＆lt; Instance-b＆gt;是实例的地址。与实例名称不同，实例地址不能以文本方式指定（尽管可以打印地址），因为它们指的是内存位置。

只需使用实例的名称，而不是定义自己的ID槽以使一个实例指向另一个实例：

         CLIPS (6.31 2/3/18)
CLIPS> 
(defclass A
    (is-a USER)
    (role concrete)
    (single-slot TheB
            (type INSTANCE)
            (allowed-classes B)
            (create-accessor read-write)))
CLIPS> 
(defclass B
    (is-a USER)
    (role concrete))
CLIPS> 
(defrule myrule
   ?b <- (object (is-a B) (name ?name))
   ?a <- (object (is-a A) (TheB ?name))
   =>
   (printout t ?a " " ?b crlf)
   (printout t ?name crlf)
   (printout t (eq ?b ?name) crlf)
   (printout t (eq ?b (instance-address ?name)) crlf))
CLIPS> (make-instance [b] of B)
[b]
CLIPS> (make-instance [a] of A (TheB [b]))
[a]
CLIPS> (agenda)
0      myrule: [b],[a]
For a total of 1 activation.
CLIPS> (run)
<Instance-a> <Instance-b>
[b]
FALSE
TRUE
CLIPS>