尝试和弹弓/尝试+差异？

Question

我正在尝试为when clj-http返回404 时编写异常处理程序.根据文档中的Exceptions部分:

clj-http将抛出一个Slingshot Stone,它可以被常规捕获(捕获Exception e ...)或者在Slingshot的try + block中捕获

尝试这一点,看起来有一些差异,我无法弄清楚:

(ns my-app.core
  (:require [clj-http.client :as client])
  (:use [slingshot.slingshot]))

(try
  (client/get "http://some-site.com/broken")
  (catch Exception e (print "I found a problem!")))

=> I found a problem!
   nil

(try+
  (client/get "http://some-site.com/broken")
  (catch Exception e (print "I found a problem!")))

=> ExceptionInfo clj-http: status 404  clj-http.client/wrap-exceptions/fn--1604 (client.clj:147)

Answer 1

如果你没有过滤子类Exception,那就可以了:

(try+
  (client/get "http://some-site.com/broken")
  (catch Object _ (print "I found a problem!")))

这里抛出的东西是带有异常元数据的本地Clojure映射,而不是传统的Java异常.

因此,如果您正在使用Slingshot,您可以在该地图上进行过滤 - 包括请求状态,返回内容,重定向等字段 - 除了具有比类更细粒度选择的块之外.例如:

(try+
  (client/get "http://some-site.com/broken")
  (catch [:status 404] {:keys [trace-redirects]}
    (print "No longer exists! (redirected through " trace-redirects ")")))