class Tilt::Mapping

def lazy_load(pattern)
  return unless @lazy_map.has_key?(pattern)
  choices = @lazy_map[pattern]
  # Check if a template class is already present
  choices.each do |class_name, file|
    template_class = constant_defined?(class_name)
    if template_class
      register(template_class, pattern)
      return template_class
    end
  end
  first_failure = nil
  # Load in order
  choices.each do |class_name, file|
    begin
      require file
      if Thread.list.size > 1
        warn "WARN: tilt autoloading '#{file}' in a non thread-safe way; " +
          "explicit require '#{file}' suggested."
      end
      # It's safe to eval() here because constant_defined? will
      # raise NameError on invalid constant names
      template_class = eval(class_name)
    rescue LoadError => ex
      first_failure ||= ex
    else
      register(template_class, pattern)
      return template_class
    end
  end
  raise first_failure if first_failure
end