From: Trans <transfire@...>
Date: 2005-07-29T11:26:02+09:00
Subject: Re: What's so special about operators, built-in classes and modules?


Daniel Brockman wrote:
> Mathieu Bouchard replied[1],
>
> >>> module A; end
> >>> module B; include A; end
> >>> module C; include A; end
> >>> class D; include C,B; end
> >>>
> >>> This is a diamond inheritance pattern.
>
> but you never replied back to him.
>
> I'd appreciate it if someone could clarify once and for all
> how the diamond inheritance problem doesn't exist in Ruby.

B/c ruby _linearizes_ the inclusions.

irb(main):001:0> module A; end
=> nil
irb(main):002:0> module B; include A; end
=> B
irb(main):003:0> module C; include A; end
=> C
irb(main):004:0> class D; include C,B ; end
=> D
irb(main):005:0> D.ancestors
=> [D, C, B, A, Object, Kernel]

Method lookup will proceed in that order.

HTH,
T.