DSL block example

gistfile1.rb

#lib 

class DSLAble
  def with_dsl(&block)
    if block.arity == 1
      block.call(self)
    else
      instance_eval(&block)
    end
  end
end

#helper

class MenuBuilder
 include DSLAble
 
  def build(&block)
    with_dsl(block)
  end

  def item(html = nil, &lazy)
    @items << (html || lazy || "")
  end

  def close
  end
end

def menu(&block)
 MenuBuilder.build block
end

# haml view
= menu do
  - item { link_to ""}
  - item link_to
  - close "Cancel"
  - item menu do |m|
    - m.item link_to ""