class Tilt::ErubiTemplate

def prepare
  @options.merge!(:preamble => false, :postamble => false, :ensure=>true)
  engine_class = @options[:engine_class] || Erubi::Engine
  @engine = engine_class.new(data, @options)
  @outvar = @engine.bufvar
  # Remove dup after tilt supports frozen source.
  @src = @engine.src.dup
  @engine
end