articles_part.rb

class ArticlesPart < Parts::Base
  def index
    return if fragment_exist?([:articles_part, Article.last])
    @articles = Articles.recent
    render
  end
end

events_part.rb

class EventsPart < Parts::Base
  def index
    # this is lazy loaded, so no need to check fragment cache
    @events = Event.limit(10)
  end
end

index.html.erb

<%= cache([:events_part, Event.last]) do %>
  <ul>
    <% @events.each do |event| %>
      <li><%= link_to event.name, [event] %></li>
    <% end %>
  </ul>
<% end %>