fakeoverloader.rb

module FakeOverloader
  def method_added(name)
    return if @__flag
    @__overloads__ ||= {}
    @__overloads__[name] ||= {}
    m = instance_method(name)
    @__overloads__[name][m.arity] = m
    @__flag = true
    define_method(name) { |*args, &block| self.class.__overloads__[name][args.size].bind(self).call(*args, &block) }
    @__flag = false
  end
  attr_reader :__overloads__
end
[29] (pry) main: 0> class Hello
[29] (pry) main: 0*   extend FakeOverloader
[29] (pry) main: 0*   def test
[29] (pry) main: 0*     puts "no args!"
[29] (pry) main: 0*   end  
[29] (pry) main: 0*   def test(arg)
[29] (pry) main: 0*     puts "one arg with value #{arg}"
[29] (pry) main: 0*   end  
[29] (pry) main: 0*   def test(arg1, arg2)
[29] (pry) main: 0*     puts "two args with values #{arg1} #{arg2}"
[29] (pry) main: 0*   end  
[29] (pry) main: 0* end  
=> nil
[30] (pry) main: 0> h = Hello.new
=> #<Hello:0x007f9c62572c08>
[31] (pry) main: 0> h.test
no args!
=> nil
[32] (pry) main: 0> h.test(1)
one arg with value 1
=> nil
[33] (pry) main: 0> h.test(1, 2)
two args with values 1 2
=> nil
[34] (pry) main: 0>