Builder is a library which RAILS will use if you end your templates in .rxml. As you can probably guess it’s very helpful in case you want to generate XML files.

xml.div(:class => “productlist”) do
  xml.timestamp(Time.now)
  @products.each do |product|
    xml.product do
      xml.productname(product.title)
      xml.price(product.price, :currency => “USD”)
    end
  end
end

<div class="productlist">
  <timestamp>Wed Mar 15 22:13:31 CET 2006</timestamp>
  <product>
    <productname>Pragmatic Programmer</productname>
    <price currency="EUR">39.96</price>
  </product>
  <product>
    <productname>Programming Ruby</productname>
    <price currency="EUR">44.95</price>
  </product>
</div>