# File lib/ffi/library.rb, line 200
    def callback(*args)
      raise ArgumentError, "wrong number of arguments" if args.length < 2 || args.length > 3
      name, params, ret = if args.length == 3
        args
      else
        [ nil, args[0], args[1] ]
      end

      options = Hash.new
      options[:convention] = defined?(@ffi_convention) ? @ffi_convention : :default
      options[:enums] = @ffi_enums if defined?(@ffi_enums)
      cb = FFI::CallbackInfo.new(find_type(ret), params.map { |e| find_type(e) }, options)

      # Add to the symbol -> type map (unless there was no name)
      unless name.nil?
        typedef cb, name
      end

      cb
    end