DSL書けねーと思ったらこれかよ！.rb

class C
  attr_accessor :age

  def initialize(&block)
    instance_eval(&block)
  end

  def name(string)
    @name = string
  end

  def address(string)
    @address = string
  end
end

C.new do
  name 'Masaya Tk'
  address 'Sapporo, Hokkaido, Japan'
  age = 23
end
#=> #<C:0x007fbc44272538 @address="Sapporo, Hokkaido, Japan", @name="Masaya Tk">

これだよこれ！.rb

class C
  def initialize(&block)
    instance_eval(&block)
  end

  def name(string)
    @name = string
  end

  def address(string)
    @address = string
  end

  def age(integer)
    @age = integer
  end
end

C.new do
  name    'Masaya Tk'
  address 'Sapporo, Hokkaido, Japan'
  age     23
end
#=> #<C:0x007fc5518162f8
#    @address="Sapporo, Hokkaido, Japan",
#    @age=23,
#    @name="Masaya Tk">

ref. rubyでselfを省略できる時、できない時 - Qiita http://qiita.com/akira-hamada/items/4132d2fda7e420073ab7