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(define (averager a b c)
(define (process-new-value)
(cond ((and (has-value? a) (has-value? b))
(set-value! c
(/ (+ (get-value a) (get-value b))
2)
me))
((and (has-value? a) (has-value? c))
(set-value! b
(- (* (get-value c) 2) (get-value a))
me))
((and (has-value? b) (has-value? c))
(set-value! a
(- (* (get-value c) 2) (get-value b))
me))))
(define (process-forget-value)
(forget-value! c me)
(forget-value! a me)
(forget-value! b me)
(process-new-value))
(define (me request)
(cond ((eq? request 'I-have-a-value)
(process-new-value))
((eq? request 'I-lost-my-value) (process-forget-value))
(else (error "Unknown request: ADDER" request))))
(connect a me)
(connect b me)
(connect c me)
me)
(define (averager a b c)
(define (process-new-value)
(cond ((and (has-value? a) (has-value? b))
(set-value! c
(/ (+ (get-value a) (get-value b))
2)
me))
((and (has-value? a) (has-value? c))
(set-value! b
(- (* (get-value c) 2) (get-value a))
me))
((and (has-value? b) (has-value? c))
(set-value! a
(- (* (get-value c) 2) (get-value b))
me))))
(define (process-forget-value)
(forget-value! c me)
(forget-value! a me)
(forget-value! b me)
(process-new-value))
(define (me request)
(cond ((eq? request 'I-have-a-value)
(process-new-value))
((eq? request 'I-lost-my-value) (process-forget-value))
(else (error "Unknown request: AVERAGER" request))))
(connect a me)
(connect b me)
(connect c me)
me)
(define (averager a b c)
(define (process-new-value)
(cond ((and (has-value? a) (has-value? b))
(set-value! c
(/ (+ (get-value a) (get-value b))
2)
me))
((and (has-value? a) (has-value? c))
(set-value! b
(- (* (get-value c) 2) (get-value a))
me))
((and (has-value? b) (has-value? c))
(set-value! a
(- (* (get-value c) 2) (get-value b))
me))))
(define (process-forget-value)
(forget-value! c me)
(forget-value! a me)
(forget-value! b me)
(process-new-value))
(define (me request)
(cond ((eq? request 'I-have-a-value)
(process-new-value))
((eq? request 'I-lost-my-value) (process-forget-value))
(else (error "Unknown request: ADDER" request))))
(connect a me)
(connect b me)
(connect c me)
me)
(define (averager a b c)
(define (process-new-value)
(cond ((and (has-value? a) (has-value? b))
(set-value! c
(/ (+ (get-value a) (get-value b))
2)
me))
((and (has-value? a) (has-value? c))
(set-value! b
(- (* (get-value c) 2) (get-value a))
me))
((and (has-value? b) (has-value? c))
(set-value! a
(- (* (get-value c) 2) (get-value b))
me))))
(define (process-forget-value)
(forget-value! c me)
(forget-value! a me)
(forget-value! b me)
(process-new-value))
(define (me request)
(cond ((eq? request 'I-have-a-value)
(process-new-value))
((eq? request 'I-lost-my-value) (process-forget-value))
(else (error "Unknown request: AVERAGER" request))))
(connect a me)
(connect b me)
(connect c me)
me)