From: Jim Freeze <jim@...>
Date: 2005-07-27T05:28:14+09:00
Subject: Re: What's so special about operators, built-in classes and modules?

* Joel VanderWerf <vjoel@path.berkeley.edu> [2005-07-27 04:52:29 +0900]:

> > Thanks Forian. For some reason I always thought that including a mod
> > would shadow old methods.
> > I suppose for my method to work (no pun intended), the standard
> > operating procedure is to:
> > 
> >   class B
> >     alias :_orig_f
> >     remove_method :f
> >     include Mod
> >   end
> > 
> Including a module is just like inheriting from a class--the module is
> above you in the ancestor list. I guess the intuitive meaning of
> "include" might be different--one might think it meant "define all
> methods from the module at this point in my class definition". Maybe
> "inherit <module>" would be a better name for the construct...

My simple thought process was always thinking that 'include'ing a Module
was the same as writing the methods myself. So

  class A
    def m
      puts "A#m"
    end
    def m
      puts :m
    end
  end
  A.new.m #=> :m

was the same thing as

  module Mod
    def m
      puts :m
    end
  end
  class A
    def m
      puts "A#m"
    end
    include Mod
  end
  A.new.m #=> :m

So, I thought it was redefining the method and the old method
was being lost if it did not have an alias.

But, as you say, it is more like inheritance.

> So would the RCR be for a construct that inserted a module between each
> instance of B and B itself?

Would be nice if the notation was external to the class
since there is no difference between:

  class A
    include Mod
    def m; puts "A#m"; end
  end

and

  class A
    def m; puts "A#m"; end
    include Mod
  end
-- 
Jim Freeze