From: Joel VanderWerf <vjoel@...>
Date: 2005-05-05T06:36:37+09:00
Subject: Re: traits (the other ones) vs. mixins

Ara.T.Howard wrote:
...
>   - Traits can be composed: trait composition is symmetric and conflicting
>   methods are excluded from the composition
...
> i cannot see how this differs from mixins?  for example:

The operation of mixing in modules is not commutative.

class C1
   include M1
   include M2
end

class C2
   include M2
   include M1
end

C1 and C2 may have radically different behavior. I guess using ruby 
modules as traits in this sense would require either some checking in 
#module_included, or some global registry of which modules are allowed 
to define which methods.