From: Yukihiro Matsumoto <matz@...>
Date: 2006-03-13T14:48:08+09:00
Subject: Re: [RCR] abstract method in Ruby

Hi,

In message "Re: [RCR] abstract method in Ruby"
    on Mon, 13 Mar 2006 12:33:45 +0900, "kwatch" <kwa@kuwata-lab.com> writes:

|>   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.
|
|Oh, I didn't realized that.

It's caused by mix-in, a kind of multiple inheritance.  The above is
rather artificial case, so that it does not cause troubles on most of
the cases, but if we want to add abstract method in the core, I think
we need to care about such cases as well.

							matz.