Dynamic constructor example with hash args

hash-args.rb

class Thing
  attr_accessor :color, :size
  def initialize args = {}
    args.each_pair do |k,v|
      if self.respond_to?(k)
        self.send("#{k}=", v)
      else
        raise ArgumentError.new "unknown property: #{k}"
      end
    end
  end
end

thing =  Thing.new(color: 'blue')
p thing
thing.size = 'medium'
p thing