From: matz@... (Yukihiro Matsumoto)
Date: 2001-06-28T11:13:45+09:00
Subject: [ruby-talk:16981] Re: Method overloading (option) Was: Re:

Hi,

In message "[ruby-talk:16972] Re: Method overloading (option) Was: Re:"
    on 01/06/28, Hugh Sasse Staff Elec Eng <hgs@dmu.ac.uk> writes:

|> If you give an object of wrong protocol, you'll get NameError (well,
|
|I'm not sure what you mean here.  (That could be because I'm implementing
|a 'protocol' on top of UDP at the moment, so I'm see the word differently 
|from you! :-))  Can you give an example of how a NameError can come from
|passing the wrong object to a user defined method, without using type
|dispatch, please?  This may help me see your Ruby Way.

  def split(obj)
    a = []
    len = obj.size
    for i in 0...len
      a.push obj[i]
    end
    a
  end

  p split("abc")        # [?a, ?b, ?c]
  p split([1,2,3])      # [1, 2, 3]
  p split(:foo)         # -:3:in `split': undefined method `size' for :foo:Symbol (NameError)
 
the "split" takes any object that responds to "size" and "[]".  "size"
and "[]" are protocol this case.

							matz.