Abstrahieren Funktionen/Vermeidung von Wiederholungen in Funktionen

Question

Ich brauche einen Hinweis auf die Abstraktion der find und check-callback Funktionen. Der Code funktioniert gut, aber es scheint, dass es viele unnötige Wiederholungen gibt. Gibt es eine elegantere Möglichkeit, sie neu zu schreiben?

;; Model 
(define-struct contact (name phone)) 
(define phonebook (list (make-contact 'adam 5551212) 
         (make-contact 'brian 5552323) 
         (make-contact 'chris 5558888))) 

;; find: (string->symbol, string->number) item (listof items) -> symbol/number/false 
(define (find type item pb) 
    (cond 
    [(empty? pb) false] 
    [(equal? (string->symbol item) (contact-name (first pb))) (contact-phone (first pb))] 
    [(equal? (string->number item) (contact-phone (first pb))) (contact-name (first pb))] 
    [else (find type item (rest pb))])) 

;; Controller 
(define (check-callback b) 
    (cond 
    [(number? (find string->symbol (text-contents a-text-field) phonebook)) 
    (draw-message a-msg (number->string (find string->symbol (text-contents a-text-field) phonebook)))] 
    [(symbol? (find string->number (text-contents a-text-field) phonebook)) 
    (draw-message a-msg (symbol->string (find string->number (text-contents a-text-field) phonebook)))] 
    [else (draw-message a-msg "Not found")])) 


;; View 
(define a-text-field 
    (make-text "Enter a name or phone number")) 

(define a-msg 
    (make-message "")) 

(define a-button 
    (make-button "Search" check-callback)) 

(create-window 
(list (list a-text-field) 
     (list a-button) 
     (list a-msg))) 

Answer 1

Da die type Variable nicht verwendet wird, ich weggelassen es aus dem Code und machte einige Refactoring:

;; find 
(define (find item pb) 
    (let* ((first-pb (first pb)) 
     (name (contact-name first-pb)) 
     (phone (contact-phone first-pb))) 
    (cond 
     [(empty? pb) #f] 
     [(equal? (string->symbol item) name) phone] 
     [(equal? (string->number item) phone) name] 
     [else (find item (rest pb))]))) 

;; Controller 
(define (check-callback pb) 
    (let ((res (find (text-contents a-text-field) pb))) 
    (draw-message a-msg 
        (cond 
        [(number? res) (number->string res)] 
        [(symbol? res) (symbol->string res)] 
        [else "Not found"])))) 

Oder Sie könnten nur auf einmal Ihren Namen und Telefon Zeichenfolge konvertieren:

;; find 
(define (find item pb) 
    (let* ((first-pb (first pb)) 
     (name (contact-name first-pb)) 
     (phone (contact-phone first-pb))) 
    (cond 
     [(empty? pb) #f] 
     [(equal? (string->symbol item) name) (number->string phone)] 
     [(equal? (string->number item) phone) (symbol->string name)] 
     [else (find item (rest pb))]))) 

;; Controller 
(define (check-callback pb) 
    (let ((res (find (text-contents a-text-field) pb))) 
    (draw-message a-msg 
        (if (res) 
        res 
        "Not found"))))