Block-based object constructor

team_builder.rb

class TeamBuilder
  attr_accessor :name
  attr_accessor :members


  def initialize(name)
    self.name    = name
    self.members = []
  end

  def player(name)
    members << name
  end

  def self.create_team(name)
    team = TeamBuilder.new(name)  # or better yet, use Object#tap here!
    yield team
    team
  end
end

TeamBuilder.create_team 'Awesome Team' do |t|
  t.player 'Adam'
  t.player 'Barry'
end

=> #<TeamBuilder:0x007f89721d3b40 @name="Awesome Team", @members=["Adam", "Barry"]>

Here's the improved version of #create_team using Object#tap

def self.create_team(name)
  TeamBuilder.new(name).tap do |team|
    yield team
  end
end