ruby_block.rb

module Liquid
  class RubyBlock < Liquid::Block
    def initialize(name, markup, tokens)
      super
      @code = @nodelist[0].to_s.gsub(/^$\n/, '')
 
      File.open('/tmp/ruby-foo.rb', 'w') {|f| f.write("#{@code}")}
      @result = `ruby /tmp/ruby-foo.rb`
    end
 
    def render(context)
       %Q[<h6>Code:</h6><pre><code>#{@code}</code></pre><h6>Output:</h6><pre class="output"><code>#{@result}</code></pre>]
    end
  end
end

Liquid::Template.register_tag('ruby', Liquid::RubyBlock)