From: Zach Dennis <zdennis@...>
Date: 2005-01-26T04:32:37+09:00
Subject: Re: Self and Ruby Comparisons

Trans wrote:
> robert,
> 
> Quite right, I'm not sure Ruby is particularly suited for role
> swapping. (Prototype-based OOP handles it gracefully) And I don't know
> how inefficent #become would be. It would be nice to think its just a
> matter of changing one pointer, but I know that's not the case.
> 
> Your role delegator is nice. At the very least it's much easier to be
> more than one thing at a time. (There's no problem with roles
> interfereing with each at the method name level is there?) Unfortuately
> I suspect that it may be nearly as inefficient as repeated using
> #become (but that's just a guess).
> 
> Thanks for the illustration, I think I'll store this for potential
> future use/exploration.
> 
> BTW, does #unrole actually work?

 From looking at the Core API it doesn't appear there is an easy way to 
remove included Modules.

I'd suggest to wrap *behaviors* into a Role object, and add that role 
object to a Person.

class Person
   @roles = []
   def add_role( r ); @roles << role
end

class Role
   @behaviors = []
   def add_behavior( b ); @behaviors << b; end
   def each_behavior( &b ); @behaviors.each{ |b| yield b.do }; end
end

class Behavior
end

class StopFireBehavior < Behavior
end

class FiremanRole < Role
   def initialze
      add_behavior( StopFireBehavior.new )
   end
end

joe = Person.new
fireman_role = Role.new( FiremanBehavior.new )
joe.add_role( FiremanRole.new )


This is just thinking outloud, not testing... so a person could have a 
role, each role is defined by a set of behaviors...?

Zach