demo_dynamic_binding.clj

(ns demo-dynamic-binding
  (:require [clojure.string :as s]))

(def verbs ["fishing" "eating" "flying" "drinking"
            "excessive drinking" "coma drinking"
            "karaoke singing"])

(defn generate-name []
  (let
      [qualities ["bold" "sneaky" "red" "dark"
            "fair-skinned" "well-tempered" "choleric" "bald" ""]

       names ["Baldrick" "Fiona" "Cheera" "Brodkin" ]
       
       things ["beaver" "weasel" "python" "Cheeta" "programmer"]]

    (format "%s, the %s %s"
            (rand-nth names)
            (rand-nth qualities)
            (rand-nth things))))

(def ^:dynamic *name* "Hadwin")

(defn step-in-storyline []
  (str *name* " goes " (rand-nth verbs)))

(defn tell-storyline []
  (dotimes [_ 10]
    (println (step-in-storyline))
    (Thread/sleep (rand-int 1000))))

(defn tell-story []
  (dotimes [_ 5]
      (.start
       (Thread.
        #(binding [*name* (generate-name)]
           (tell-storyline))))))


(defn test-storyline []
  (binding [*name* "Edward, the almost-bald programmer"]
    (let [step-in-epic-journey (step-in-storyline)]
      (if-not
          (s/starts-with?
           step-in-epic-journey
           "Edward, the almost-bald programmer goes")
        (throw (Exception. (str "OOOOOPS! Test failed. "
                               step-in-epic-journey
                               " does not start with Edward...")))
        :success))))