From: Trans <transfire@...>
Date: 2008-07-16T12:49:40+09:00
Subject: Re: Is there a way to call include for an object instance?



On Jul 15, 11:38 pm, Chris Olsen <olsen.ch...@gmail.com> wrote:
> 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.
>
> It can be seen at the bottom by the comments I made that the includes
> are being added on to the Stats class and the methods from the first
> include are still there after the second include.  Is there a way to add
> an include to an object instance rather than a class?
>
> Thanks for the help
>
> ########
> 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
>
> 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
>
> class Stats
>
>   def self.create_by_sport(sport)
>     s = Stats.new
>     s.sport = sport
>     return s
>   end
>
>   def sport=(sport)
>     Stats.instance_eval do  # have tried to use self.instance_eval
>       eval("include #{sport.capitalize}Stats")
>     end
>   end

Couple of ways. One is to use the singleton.

   def sport=(sport)
     (class << self; self; end).class_eval %{
       include #{sport.capitalize}Stats
     }
   end

But I think you might want to reconsider and use delegation instead.

T.