Simple Ruby DSL to generate XML

readme.md

I've tried to do some thing differently from Jonas and Torgeir.

Some notes:

• I've used 1.9 hash syntax
• I've tried to remove most variables, and use methods instead (I like reading xml instead of @xml)
• I don't like the fact that I have to join the result, as it's now an array, not a string
• I tried to use a block to handle indentation

create_xml.rb

require './xmldsl'

Twitter = Struct.new :name, :avatar, :text
twitters = []
5.times { twitters << Twitter.new("Jonas", "/profile.png", "Hello World!") }

xml = XML.generate do
  html do
    body do
      twitters.each do |tw|
        img src: tw.avatar, alt: tw.name, width: 25, height: 25
        content [" : ", tw.text]
        br
        br
      end
      form action: '/page', method: 'post' do
          input type: 'text', name: 'str', maxlength: 3, size: 3
          input type: 'submit', value: 'page'
      end
    end
  end
end

open('sample_twitters.html', 'w') {|f| f.puts xml}
puts xml

xmldsl.rb

class XML
  def self.generate &block
    XML.new.xml_generate &block
  end

  def xml_generate &block
    instance_eval(&block).join
  end

  def xml
    @xml or @xml = []
  end

  def method_missing name, args = {}
    xml << "#{indent}<#{name} #{attributes(args)}"
    if block_given?
      xml << ">\n"
      indent do
        yield
      end
      xml << "#{indent}</#{name}>\n"
    else
      xml << "/>\n"
    end
  end

  def indent
    @indent or @indent = 0

    if block_given?
      @indent += 3
      yield
      @indent -= 3
    else
      " "*@indent
    end
  end

  def attributes args
    args.map { |key, value| "#{key}='#{value}'"}.join(" ")
  end

  def content txt
    xml << "#{indent}#{[txt].join}\n"
  end
end