有沒有辦法讓CLIPS中的插槽只有唯一的值

Question

(deftemplate Employee 
    (slot employee-id) 
    (slot employee-name) 
    (slot Role) 
    (slot Designation)) 

(deffacts Employees 
    (employee (employee-name X) (employee-id 1) (Role CS) (Designation TA)) 
    (employee (employee-name Y) (employee-id 2) (Role CS) (Designation SA)) 
    (employee (employee-name Z) (employee-id 3) (Role CIS) (Designation TA)) 
    (employee (employee-name W) (employee-id 4) (Role SE) (Designation SA)) 
    (employee (employee-name Q) (employee-id 5) (Role CIS) (Designation TA)) 
    (employee (employee-name U) (employee-id 1) (Role CS) (Designation TA))) 

在上例中，我輸入了兩次員工ID。我如何定義員工ID是唯一的？

Answer 1

CLIPS> (defglobal ?*id* = 0) 
CLIPS> 
(deffunction next-id() 
    (bind ?*id* (+ ?*id* 1))) 
CLIPS> 
(deftemplate employee 
    (slot employee-id (default-dynamic (next-id))) 
    (slot employee-name) 
    (slot Role) 
    (slot Designation)) 
CLIPS> 
(deffacts Employees 
    (employee (employee-name X) (Role CS) (Designation TA)) 
    (employee (employee-name Y) (Role CS) (Designation SA)) 
    (employee (employee-name Z) (Role CIS) (Designation TA)) 
    (employee (employee-name W) (Role SE) (Designation SA)) 
    (employee (employee-name Q) (Role CIS) (Designation TA)) 
    (employee (employee-name U) (Role CS) (Designation TA))) 
CLIPS> (reset) 
CLIPS> (facts) 
f-0  (initial-fact) 
f-1  (employee (employee-id 1) (employee-name X) (Role CS) (Designation TA)) 
f-2  (employee (employee-id 2) (employee-name Y) (Role CS) (Designation SA)) 
f-3  (employee (employee-id 3) (employee-name Z) (Role CIS) (Designation TA)) 
f-4  (employee (employee-id 4) (employee-name W) (Role SE) (Designation SA)) 
f-5  (employee (employee-id 5) (employee-name Q) (Role CIS) (Designation TA)) 
f-6  (employee (employee-id 6) (employee-name U) (Role CS) (Designation TA)) 
For a total of 7 facts. 
CLIPS>