Clojure的DEFTYPE和协议

Question

我在我的（NS处理程序）这个Clojure的代码

(defprotocol ActionHandler 
    (handle [params session])) 

(defrecord Response [status headers body]) 

(deftype AHandler [] 
    ActionHandler 
    (handle [params session] 
      (Response. 200 {"Content-Type" "text/plain"} "Yuppi, a-handler works"))) 


(deftype BHandler [] 
    ActionHandler 
    (handle [params session] 
      (Response. 200 {"Content-Type" "text/plain"} "YES, the b-handler is ON"))) 

(deftype CHandler [] 
    ActionHandler 
    (handle [params session] 
      (Response. 200 {"Content-Type" "text/plain"} "C is GOOD, it's GOOD!"))) 

在我core.clj我得到这个代码（省略几行和命名空间的东西）：

(handle the-action-handler params session) 

动作处理程序是deftype处理程序之一的有效实例。 当我尝试编译我得到这个错误：

java.lang.IllegalArgumentException: No single method: handle of interface: handlers.ActionHandler found for function: handle of protocol: ActionHandler 

我没有读到时的参数数目无效传递到协议功能误导性的错误消息，但是，这并不像你所看到的情况。

可能是什么问题？有什么建议么？ Greg

Answer 1

我相信你是通过两个参数而不是一个。发生什么事是协议方法的第一个参数是this参数。

试试这个

(defprotocol ActionHandler 
    (handle [this params session])) 

(defrecord Response [status headers body]) 

(deftype AHandler [] 
    ActionHandler 
    (handle [this params session] 
      (Response. 200 {"Content-Type" "text/plain"} "Yuppi, a-handler works"))) 


(deftype BHandler [] 
    ActionHandler 
    (handle [this params session] 
      (Response. 200 {"Content-Type" "text/plain"} "YES, the b-handler is ON"))) 

(deftype CHandler [] 
    ActionHandler 
    (handle [this params session] 
      (Response. 200 {"Content-Type" "text/plain"} "C is GOOD, it's GOOD!")))