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*default-data-reader-fn* (clj)

(source)

variable

When no data reader is found for a tag and *default-data-reader-fn* is non-nil, it will be called with two arguments, the tag and the value. If *default-data-reader-fn* is nil (the default), an exception will be thrown for the unknown tag.

Examples

clojure 
(deftest division
  (is (= clojure.core// /))
  (binding [*ns* *ns*]
    (eval '(do (ns foo
                 (:require [clojure.core :as bar])
                 (:use [clojure.test]))
               (is (= clojure.core// bar//))))))

(deftest unknown-tag
  (let [my-unknown (fn [tag val] {:unknown-tag tag :value val})
        throw-on-unknown (fn [tag val] (throw (RuntimeException. (str "No data reader function for tag " tag))))
        my-uuid (partial my-unknown 'uuid)
        u "#uuid \"550e8400-e29b-41d4-a716-446655440000\""
        s "#never.heard.of/some-tag [1 2]" ]
    (binding [*data-readers* {'uuid my-uuid}
              *default-data-reader-fn* my-unknown]
      (testing "Unknown tag"
        (is (= (read-string s)
               {:unknown-tag 'never.heard.of/some-tag
                :value [1 2]})))
      (testing "Override uuid tag"
        (is (= (read-string u)
               {:unknown-tag 'uuid
                :value "550e8400-e29b-41d4-a716-446655440000"}))))

    (binding [*default-data-reader-fn* throw-on-unknown]
      (testing "Unknown tag with custom throw-on-unknown"
        (are [err msg form] (thrown-with-msg? err msg (read-string form))
             Exception #"No data reader function for tag foo" "#foo [1 2]"
             Exception #"No data reader function for tag bar/foo" "#bar/foo [1 2]"
             Exception #"No data reader function for tag bar.baz/foo" "#bar.baz/foo [1 2]")))
typedclojure/typedclojure 
(ns ^:no-doc typed.ann.clojure
  "Type annotations for the base Clojure distribution."
  #?(:cljs (:require-macros [typed.ann-macros.clojure :as macros]))
  (:require [clojure.core :as cc]
            [typed.clojure :as t]
            #?(:clj [typed.ann-macros.clojure :as macros])
            #?(:clj typed.ann.clojure.jvm) ;; jvm annotations
            #?(:clj clojure.core.typed))
  #?(:clj
     (:import (clojure.lang PersistentHashSet PersistentList
                            APersistentMap #_IPersistentCollection
                            #_ITransientSet
                            IRef)
              (java.util Comparator Collection))))

cc/*1 t/Any
cc/*2 t/Any
cc/*3 t/Any
cc/*e #?(:cljs t/Any :default (t/U nil Throwable))
#?@(:cljs [] :default [
cc/*agent* (t/U nil (t/Deref t/Any) #_(t/Agent t/Any))
cc/*allow-unresolved-vars* t/Any
cc/*data-readers* (t/Map t/Sym t/AnyVar)
cc/*default-data-reader-fn* (t/U nil [t/Any t/Any :-> t/Any])
cc/*fn-loader* t/Any
cc/*math-context* t/Any
cc/*source-path* t/Str
cc/*use-context-classloader* t/Any
])
cc/*assert* t/Any