計劃格式幫助

Question

我一直在爲學校開發一個項目，該項目從一個類文件中獲取函數並將其轉換爲對象/類。這個任務都是關於方案中的面向對象編程。

但是我的問題是我的代碼格式不正確。

無論何時我給它一個文件傳遞給列表中的類的方法，它都會給我提供的輸出，使得類永遠不會被聲明。我不能爲我的生活弄清楚如何讓圓括號包裝方法列表來刪除。

我真的很感激任何幫助。

下面是輸出，類文件和代碼。

(define pointInstance 
    (let ((myx 1) (myy 2)) 
    (lambda msg 
     (cond 
     (((eq? (car msg) getx) myx) 
     ((eq? (car msg) gety) myy) 
     ((eq? (car msg) setx) (set! myx x)) 
     ((eq? (car msg) show) (begin (display "[") (display myx) (display ",") (display myy) (display "]")))))))) 

如果你看一下剛剛COND後，你會看到所有的EQ語句是如何包含在列表中。除非他們沒有被頂層列表所包裹，否則我無法讓它正常工作。

;;;; PART1 --- A super-easy set of classes. Just models points and lines. Tests all of >the 
;; basics of class behavior without touching on anything particularly complex. 

(class pointInstance (parent:) (constructor_args:) 
    (ivars: (myx 1) (myy 2)) 
    (methods: 
    (getx() myx) 
    (gety() myy) 
    (setx (x) (set! myx x)) 
    (show() (begin (display "[") (display myx) (display ",") (display myy) (display "]"))) 
    )) 



(require (lib "trace.ss")) 

;; Continue reading until you hit the end of the file, all the while 
;; building a list with the contents 
(define load-file 
(lambda (port) 
(let ((rec (read port))) 
(if (eof-object? rec) 
'() 
(cons rec (load-file port)))))) 

;; Open a port based on a file name using open-input-file 
(define (load fname) 
(let ((fport (open-input-file fname))) 
(load-file fport))) 



;(define lis (load "C:\\Users\\Logan\\Desktop\\simpletest.txt")) 
;(define lis (load "C:\\Users\\Logan\\Desktop\\complextest.txt")) 
(define lis (load "C:\\Users\\Logan\\Desktop\\pointinstance.txt")) 

;(display (cdaddr (cdddar lis))) 

(define makeMethodList 
    (lambda (listToMake retList) 
    ;(display listToMake) 
    (cond 
     [(null? listToMake) 
     retList 
     ;(display "The list passed in to parse was null") 
     ] 
     [else 
     (makeMethodList (cdr listToMake) (append retList (list (getMethodLine   listToMake)))) 
     ] 
     ) 
    )) 
;(trace makeMethodList) 

;this works provided you just pass in the function line 
(define getMethodLine 
    (lambda (functionList) 
    `((eq? (car msg) ,(caar functionList)) ,(caddar functionList)))) 

(define load-classes 
    (lambda paramList 
    (cond 
    [(null? paramList) (display "Your parameters are null, man.")] 
[(null? (car paramList))(display "Done creating class definitions.")] 
[(not (null? (car paramList))) 

    (begin 
    (let* ((className (cadaar paramList)) 
      (classInstanceVars (cdaddr (cddaar paramList))) 
      (classMethodList (cdr (cadddr (cddaar paramList)))) 
      (desiredMethodList (makeMethodList classMethodList '())) 

      ) 
     ;(display "Classname: ") 
     ;(display className) 
     ;(newline)(newline) 

     ;(display "Class Instance Vars: ") 
     ;(display classInstanceVars) 
     ;(newline)(newline) 

     ;(display "Class Method List: ") 
     ;(display classMethodList) 
     ;(newline) 

     ;(display "Desired Method List: ") 
     ;(display desiredMethodList)) 
     ;(newline)(newline) 

;---------------------------------------------------- 
;do not delete the below code!` 
     `(define ,className 
     (let ,classInstanceVars 
      (lambda msg 
      ;return the function list here 
      (cond ,(makeMethodList classMethodList '()))) 
      )) 
;--------------------------------------------------- 
))] 
) 
)) 

(load-classes lis) 
;(load-classes lis) 
;(load-classes-helper lis) 
;(load-classes "simpletest.txt") 
;(load-classes "complextest.txt") 

;method list 
;(display (cdr (cadddr (cddaar <class>)))) 

Answer 1

在cond的第1個子句中有太多左括號。

IE：

(((eq? (car msg) getx) myx) 
^ 

更新時間：

你在找這個？

(cond ,@(makeMethodList classMethodList '()) 
     ^^ 

或者，你可以這樣做：

(cond . ,(makeMethodList classMethodList '())