[ruby-talk:11804] Same method name in same class with diff params?

A RubyNuby friend has a question, and being a RubyNuby myself, I
didn't readily have an answer:

He has a class that wants to do something like:

class Foo
  def bar()
    # do something
  end

  def bar(param)
    # do something else but similar
  end
end

Apparently bar() and bar(param) are not considered different method
signatures.  I've read the pickaxe book, but may have missed this.

Does he have to do a bar(*b) and then handle the case of having / not
having args from the array inside of the method?  Or perhaps,
bar(a=nil) - or some other default - for the bar() case?

Thanks,

Guerry