module FFI::Library

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?
    @ffi_callbacks = Hash.new unless defined?(@ffi_callbacks)
    @ffi_callbacks[name] = cb
  end
  cb
end