hashifiable.rb

module Hashifiable
  def hashify(*args)
    hashified = {}

    args.each do |arg|
      case arg
      when Symbol
        hashified[arg] = lambda { |obj| obj.send(arg) }
      when Hash
        arg.each do |key, proc|
          hashified[key] = lambda { |obj| obj.instance_exec(&proc) }
        end
      end
    end

    ## Defines to_hash method dinamically with the key/values specified
    ## in *args.
    define_method :to_h do
      hashified.to_a.inject({}) do |result, (key, callable)|
        result[key] = callable.call(self)
        result
      end
    end

    alias_method :to_hash, :to_h
  end
end