Throw an error in cljc code

Question

I'm writing a cljc library that needs to throw an error. This is how I tried to do it:

(def ErrorType #?(:clj java.lang.Exception
                  :cljc js/Error)

(throw (new ErrorType "message"))

But this code fails with an error saying "couldn't find class ErrorType". What is the correct way of doing this?

Answer 1

I think you mean :cljs instead of :cljc.

I suspect the main issue here is that new is a special form that wants a symbol recognizable by the compiler, rather than a runtime variable. You can use ex-info portably, but if you want to leverage specific error types of the host platform, you might try an approach similar to this:

(defn oob-error
  [message]
  #?(:clj (new ArrayIndexOutOfBoundsException message)
     :cljs (new js/RangeError message))

(throw (oob-error "message"))

Answer 2

I think you can construct an exception with ex-info and throw it in both Clojure and ClojureScript portably right?