From: ts <decoux@...>
Date: 2003-01-27T02:56:05+09:00
Subject: Re: "exclude" (was: Re: cascading configuration variables)

>>>>> "W" == Wilbert Berendsen <wilbert@oswf.org> writes:

W> But this is all imaginary. In reality, is a mixed-in module really like a 
W> superclass? because a module can mix-in (include) another module in at 
W> any time of its life, but classes cannot inherit a superclass later on.

 Well, with my previous example

   module A 
      A_nice_constant = 12
   end
   module B
      include A 
   end
   module C
      include A 
   end

   class D         # D inherit from Object
                   # search path is : D ==> Object

      include C    # ruby make the include : first C then A
                   # search path is : D ==> C ==> A ==> Object

      include B    # ruby make the include : first B, then A
                   # search path is : D ==> B ==> C ==> A ==> Object
                   # A is not included twice
   end


 At this step, ruby has lost the information that `A' was provided by `B'
 and `C'


Guy Decoux