CODEWITHSUNDEEP
clojurenamespacesprotocols
Jeremy Field
Jeremy Field

Reputation: 692

Why IllegalArgumentException "interface is not a protocol" when importing a Clojure protocol?

I followed Cursive's suggestion to Import class when using extend-protocol in a different namespace to the one where defprotocol occurred.

(ns the.first)
(defprotocol AProtocol
  (method [this]))

(ns the.second
  (:import (the.first AProtocol)) ; <= Cursive suggested this...
(extend-protocol AProtocol ; <= ...because this wasn't in scope.
  AType
  (method [this] ...))

I tore my hair out a little at the IllegalArgumentException: interface the.first.AProtocol is not a protocol.

Upvotes: 0

Views: 101

Answers (1)

Jeremy Field
Jeremy Field

Reputation: 692

Then I realised I should have ignored the IDE's hint, and :required the protocol (and methods, for convenience).

(ns the.second
  (:require [the.first :refer [AProtocol amethod]]))

Only obvious in retrospect.

Upvotes: 2

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