Hi,

In message "Re: [RCR] abstract method in Ruby"
    on Sun, 12 Mar 2006 16:38:44 +0900, "kwatch" <kwa / kuwata-lab.com> writes:

|The following code itself describes that method each() is abstract.
|It's more descriptive.
|
|  module Enumerable
|    abstract_method :each
|    def map
|      arr = []
|      each { |elem| arr << yield(elem) }
|      arr
|    end
|  end

I'm afraid that it doesn't work for some cases, for example:

  class Base
    def each
      ...
    end
  end

  class Derived < Base
    include Enumerable
    ...
  end

The abstract "each" method defined in Enumerable overrides the "each"
in the Base class.  I'm not against the idea of abstract (or deferred)
method, but sometimes it's not that simple.

							matz.