From: Tachikoma <ikari.shinji.eva@...>
Date: 2008-07-16T17:05:16+09:00
Subject: Re: Is there a way to call include for an object instance?

On Jul 16, 12:11 pm, "Eric I." <rubytrain...@gmail.com> wrote:
> Hi Chris,
>
> > I need to be able to create an object and, based on the param that I
> > pass in on the class create_for_sport method, create an object with the
> > proper module included.
>
> You can call extend on an instance to mix in a modules instance
> methods to the instance (and leaving the class itself alone).  In your
> code, we also need to convert your string to a reference to the module
> as well, via a call to const_get.  And this would be your new sport=
> method:
>
>   def sport=(sport)
>     extend(self.class.const_get(sport.capitalize + "Stats"))
>   end
>
> I believe that will work for you.
>
> Eric
>
> ====
>
> LearnRuby.com offers Rails & Ruby HANDS-ON public & ON-SITE workshops.
> Please visithttp://LearnRuby.comfor all the details.

you should put module(s) into class ,to ensure class Stats has the
permission of module,so try following code

class Stats
  module HockeyStats
    def to_sport
      puts "hockey"
    end

    def scoring_percentage
      0.34
    end

    def before_save
      puts "in the hockey before save"
    end

  end

  module SoftballStats
      def to_sport
        puts "softball"
      end

      def batting_average
        0.563
      end

      def before_save
        puts "in the softball before save"
      end

  end

  def self.create_by_sport(sport)
    s = Stats.new
    s.sport = sport
    return s
  end

  def sport=(sport)
    eval "extend #{sport.to_s.capitalize}Stats"
  end

end