not really useful config loader

env.clj

(ns my.env
  (:require [clojure.edn :as edn]))

(defn- get-resource [path]
  (let [classloader (java.lang.ClassLoader/getSystemClassLoader)]
    (.getResource classloader path)))

(defn- read-config-file []
  (let [url (get-resource "config.edn")]
    (slurp url)))

(defn- parse-config-file [string]
  (edn/read-string string))

(comment
  "Example: get a nested value from the config file (config.edn on the classpath"
  (env/

(defn- delayed-config []
  (delay (do (println "reading configuration...")
             (parse-config-file (read-config-file)))))

(def ^:private config
  (atom (delayed-config)))

(defn get [& paths]
  (get-in @@config paths))

(defn reload! []
  (reset! config (delayed-config)))

(comment
  "Example: read a value from the configuration file"
  {:dbpath "file://tmp/database"}
  
  (my.env/get :dbpath) ;=> "file://tmp/database"
  
  "Example: read a nested value from the configuration file"
  {:pool {:object {:type :special}}}
  
  (my.env/get :pool :type :count) ;=> :specal
  
  "Example: reload the configuration file"
  
  (my.env/reload!)
  (my.env/get :dbpath) ; reads the file again
  
)

This isn't super useful, because things like environ exist, but I didn't know that when I wrote this.

The novel (to me at the time) thing I did here was to store a delay in an atom, which means that I could memoize reading the configuration file until it's used, but still be able to force a reload (which I need, since I edit the config a good amount in development).