SharkNativeWrapper(SharkBuilder* builder,
                     methodHandle  target,
                     const char*   name,
                     BasicType*    arg_types,
                     BasicType     return_type)

  {- -------------------------------------------
  (1) フィールドの初期化を行った後, 
      SharkNativeWrapper::initialize() を呼び出す.
      ---------------------------------------- -}

        : SharkCompileInvariants(NULL, builder),
          _target(target),
          _arg_types(arg_types),
          _return_type(return_type),
          _lock_slot_offset(0) { initialize(name); }