Initialize object without new

init_without_new.rb

class Team

  attr_accessor :name, :country
  class << self
    undef_method :new
  end

  def self.constructor(*args)
    obj = allocate
    obj.send(:initialize, *args)
    obj
  end
end

class Barcelona < Team
  def initialize(name, country)
    @name     = name
    @country  = country
  end
end

class ChicagoBulls < Team
  def initialize(name, city, country)
    @name     = name
    @city     = city
    @country  = country
  end
end

require 'test/unit'
class TestBarcelonaTeam < Test::Unit::TestCase
  def test_initialize_barcelona
    team = Barcelona.constructor("Barcelona", "Spain")
    assert team.is_a? Team
  end

  def test_initialize_chicago
    team = ChicagoBulls.constructor("Chicago Bulls", "Chicago", "United States")
    assert team.is_a? Team
  end
end