<%
   previous_date = @start_date << 1
   next_date = @start_date >> 1
%>

<% with_options(:types => ["CommunityEvent"]) do |opt| %>
  [ <%= link_to("前月", opt.community_threads_path(:year => previous_date.year, :month => previous_date.month))   %> ]
  [ <%= link_to("今月", opt.community_threads_path(:year => Date.today.year, :month => Date.today.month))   %> ]
  [ <%= link_to("次月", opt.community_threads_path(:year => next_date.year, :month => next_date.month))   %> ]
<% end %>
<br />

<%= h l(@start_date, :format => :year_month) %>
