In article <Pine.LNX.3.96.1010528013952.23673A-100000 / relayer>,
Mathieu Bouchard <matju / sympatico.ca> wrote:
>Three months ago I have written:
>
>module ArithInterface
>	def +(other); raise NotImplementedError; end
>	def -@; raise NotImplementedError; end
>end
>
>module ArithMixin
>	include ArithInterface
>	def -(other)
>		self + - other
>	end
>end
>
>and then I stopped there. ;-)

Perhaps I will work on this, as an exercise to learn Ruby.

It seems to me that when designing code for Ruby, it is
always best to write something as a module rather than a 
class if possible, because a module is more flexible. 
Is this correct as a general rule of principle?

--Mirian