asm.clj

(ns asm-test.test-class
  (:import [clojure.asm ClassWriter ClassVisitor Opcodes Type]
           [clojure.asm.commons GeneratorAdapter Method]
           [clojure.lang DynamicClassLoader Compiler RT]))

(def cw (ClassWriter. ClassWriter/COMPUTE_MAXS))
(. cw (visit Opcodes/V1_5 Opcodes/ACC_PUBLIC
             "asm_test/test_class/TestClass" nil "java/lang/Object" (make-array String 0)))

(let [m (Method. "doit" Type/VOID_TYPE (into-array Type [(Type/getType String)]))
      gen (GeneratorAdapter. (bit-or Opcodes/ACC_PUBLIC Opcodes/ACC_STATIC)
                             m nil nil cw)]
  (.visitCode gen)
  (. gen push "clojure.core")
  (. gen push "*out*")
  (. gen invokeStatic (Type/getType clojure.lang.RT) (. Method getMethod "clojure.lang.Var var(String,String)"))
  (. gen invokeVirtual (Type/getType clojure.lang.Var) (. Method getMethod "java.lang.Object get()"))
  (. gen dup)
  (. gen checkCast (Type/getType java.io.PrintWriter))
  (. gen loadArg 0)
  (. gen invokeVirtual (Type/getType java.io.PrintWriter) (. Method getMethod "void println(String)"))
  (.returnValue gen)
  (.endMethod gen))

(.visitEnd cw)

(. @Compiler/LOADER (defineClass "asm_test.test_class.TestClass" (.toByteArray cw) nil))

(import 'asm_test.test_class.TestClass)