使用COND

Question

簡單defun定義我想一些基本的東西了在CL，不明白爲什麼這個不能編譯，編譯器錯誤：

(defun ifelse (the-test) 
    (cond ((the-test) (format t "passed test")) 
    (t (format t "failed test")))) 

編譯器說：

; caught STYLE-WARNING: 
; undefined function: THE-TEST 

我已經做了類似與if無故障：

(defun test-if (the-test) 
    (if the-test 
     (format t "passed") 
     (format t "failed"))) 

編譯器不抱怨。 cond不會以同樣的方式工作，因爲它們都測試條件？

; in: DEFUN IFELSE 
;  (DEFUN IFELSE (THE-TEST) 
;  (COND ((THE-TEST) (FORMAT T "passed test, true!")) 
;    (T (FORMAT T "failed test, boo hoo")))) 
; --> PROGN EVAL-WHEN 
; ==> 
; (SB-IMPL::%DEFUN 'IFELSE 
;     (SB-INT:NAMED-LAMBDA IFELSE 
;      (THE-TEST) 
;      (BLOCK IFELSE (COND (# #) (T #)))) 
;     NIL 'NIL (SB-C:SOURCE-LOCATION)) 
; 
; caught STYLE-WARNING: 
; The variable THE-TEST is defined but never used. 

;  (THE-TEST) 
; 
; caught STYLE-WARNING: 
; undefined function: THE-TEST 
; 
; compilation unit finished 
; Undefined function: 
;  THE-TEST 
; caught 2 STYLE-WARNING conditions 

Answer 1

從完整的編譯器錯誤

(DEFUN IFELSE (THE-TEST) 
(COND ((THE-TEST) ... 

你的代碼是不同的：

(defun ifelse (the-test) 
    (cond (the-test ... 

過程中你的測試你可能改變你的代碼。

在您的實際代碼，您使用的變量的測試

在編譯器錯誤的函數試圖調用函數（的測試）