From: Trans <transfire@...>
Date: 2007-10-13T21:41:38+09:00
Subject: Re: Generation of initialize



On Oct 13, 5:20 am, arcadiorubiogar...@gmail.com wrote:
> Hi everyone,
>
> I'm new to Ruby. I'm looking for an elegant solution to a simple
> problem.
>
> I have some classes like this one in my code:
>
> class A
>
> attr_reader :a1, a2
>
> def initialize(a1, a2)
>   @a1 = a1
>   @a2 = a2
> end
>
> end
>
> I'm looking for a way in order not to have to define the initialize
> method in each class. Struct doesn't fit my needs since due to single
> inheritance I can't have any other superclass, and I would like to.
>
> Any suggestions?

You could create an attr_initializer, something like:

  module MyInitSystem
    # extend hack
    def self.included(base)
      base.extend ClassMethods
    end

    module ClassMethods
      attr_reader :attr_initializers
      def attr_initializer(*args)
        @attr_initializers ||= []
        @attr_initializers.concat(args)
        attr_reader *args
      end
    end

    def initialize(*args)
      self.class.attr_initializers.each_with_index do |a,i|
        instance_variable_set("@#{a}", args[i])
      end
    end
  end

  class A
    include MyInitSystem

    attr_initializer :a, :b
  end

Albeit, I'd use a hash to populate my object by var name.

T.