mefesto

(let [method (.getMethod Long "valueOf" (into-array Class [String]))]
  (.invoke method Long (into-array Object ["123"])))

mefesto

(let [method (.getMethod String "indexOf" (into-array Class [String Integer/TYPE]))]
  (.invoke method "hello" (into-array Object ["ll" 0])))

mefesto

(with-open [rdr (io/reader (io/file "file.txt"))]
  (doseq [line (line-seq rdr)]
    (println "line:" line)))

(with-open [lines (line-seq (io/file "file.txt"))]
  (doseq [line lines]
    (println "line:" line)))

mefesto

(defn call [f & args]
  (when f (apply f args)))

(def callbacks
  {:do-this #(println "this")
   :do-that #(println "that")})

(call (:do-this callbacks)) ;; prints "this"
(call (:do-that callbacks)) ;; prints "that"
(call (:do-other callbacks)) ;; nil

mefesto

(deftype Foo []
  Object
  (equals [this x]
    (.. this getClass (isInstance x))))

(let [f (Foo.)]
  (.equals f f)) ; false, creates problems when looking up items in map

mefesto

(ns blah.test-mystuff
  (:use clojure.test))

(defn my-fixture [f]
  (println "setup")
  (f)
  (println "tear down"))

(use-fixtures :each my-fixture)

mefesto

(ns mefesto.qsort)

(set! *warn-on-reflection* true)

(defn- aswap! [^doubles vals ^ints idxs ^long x ^long y]
  (let [val (aget vals x)
        idx (aget idxs x)]
    (aset vals x (aget vals y))
    (aset vals y val)
    (aset idxs x (aget idxs y))

mefesto

(require '[clojure.contrib.sql :as sql])

(sql/with-connection dbspec
  (sql/transaction
    (sql/do-prepared
      "update mytable set counter = counter + 1
       where id = ?"
      [1000])))

mefesto

(defn encode [^String str]
  (ChannelBuffers/wrappedBuffer 
    ^byte[] (into-array (concat (.getBytes "hello" "UTF-8") [(byte 0)]))))

mefesto

(defn encode [^String str]
  (ChannelBuffers/wrappedBuffer 
    (.getBytes str "UTF-8")
    (byte-array [(byte 0)])))