From: Su Zhang <su.comp.lang.ruby@...>
Date: 2011-12-03T05:13:23+09:00
Subject: Re: Inverse Operation of Module#include

On 12/2/2011 6:22 AM, Isaac Sanders wrote:
> I would suggest an Adapter pattern use here. IF there is something that has
> functionality that you want to have shared, and one thing changes, I would
> make different subclasses. Example:
>
> class Team # Base class
>
> def play
>    raise "You should use a subclass of Team."
> end
>
> end

Hi Issac,

What if Team inherits from Group, and both FootballTeam and BaseballTeam 
depend on some common interface defined in both Team and Group, and I 
want to alter the implementations for Group at runtime?

For example:

class Group
   def cheer
     # drink_beer or have_barbecue?
   end
end

class Team < Group
   def consult
     analyze_tactics
   end
end

class FootballTeam < Team
   def cheer
     super
     shout
   end
end

class BaseballTeam < Team
   def cheer
     super
     roar
   end
end

team = FootballTeam.new
team.cheer
team.consult

team = BaseballTeam.new
team.cheer
team.consult

Both types of team share the common Team#consult method, but I cannot be 
sure if I should do drink_beer or have_barbecue in Group#cheer until 
runtime, and I want to separate them as different implementations. With 
module mixin, all the implementations are nicely injected into the 
inheritance chain. If we derive from Group, the derived class will not 
be on the same inheritance chain as FootballTeam or BaseballTeam.

Su