module Function
  module Behavior
    % Dynamically define call and [] as methods that receives
    % up to 20 arguments and forward them to the function.
    20.times [], do (i, acc)
      contents = [
        {
          'clause, __LINE__, acc, [], [
            { 'call, __LINE__, {'var, __LINE__, 'self}, acc }
          ]
        }
      ]

      define_erlang_method __FILE__, __LINE__, '[], acc.length, contents
      define_erlang_method __FILE__, __LINE__, 'call, acc.length, contents
      [{ 'var, __LINE__, '"V#{i}" }|acc]
    end

    def apply(args)
      Erlang.apply(self, args)
    end

    def arity
      { 'arity, value } = Erlang.fun_info(self, 'arity)
      value
    end
  end
end