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POIssue with protocols in Clojure: "No single method: ..." error
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copied!<blockquote> <p><strong>Possible Duplicate:</strong><br> <a href="https://stackoverflow.com/questions/5401378/do-clojure-protocols-allow-one-to-have-a-variadic-method-the-way-funcions-do-wi">Do clojure protocols allow one to have a variadic method the way funcions do (with an ampersand)?</a> </p> </blockquote> <p>I'm getting this error when running some Clojure code using a protocol:</p> <pre><code>Exception in thread "main" java.lang.IllegalArgumentException: No single method: add_component of interface: questar.entity.Entity found for function: add-component of protocol: Entity, compiling:(questar/entity.clj:17) </code></pre> <p>Here's the code in question:</p> <pre><code>(defprotocol Entity (add-component [this cname & args]) (update-component [this cname f & args]) (remove-component [this cname]) (get-component [this cname]) (has-component? [this cname])) (extend-protocol Entity clojure.lang.IPersistentMap (add-component [this cname & args] (assoc entity cname (apply new-component cname args))) (update-component [this cname f & args] (let [component (get-component this cname)] (add-component this cname (apply f component args)))) (remove-component [this cname] (dissoc this cname)) (get-component [this cname] (this cname)) (has-component? [this cname] (contains? this cname)) clojure.lang.IDeref (add-component [this cname & args] (alter this (apply add-component cname args))) (update-component [this cname f & args] (alter this (apply update-component cname f args))) (remove-component [this cname] (alter this remove-component cname)) (get-component [this cname] (get-component this @cname)) (has-component? [this cname] (has-component? this @cname))) </code></pre> <p>I know this can be related to the arity, but everything looks correct to me. Is this because it can't figure out which version of add-component to call?</p> <p>Thanks!</p>

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