/ Ruby on Rails
/
method

cycle

cycle(first_value, *values)
public

Creates a Cycle object whose to_s method cycles through elements of an array every time it is called. This can be used for example, to alternate classes for table rows: 

  <% @items.each do |item| %>
    <tr class="<%= cycle("even", "odd") -%>">
      <td>item</td>
    </tr>
  <% end %>

You can use named cycles to allow nesting in loops. Passing a Hash as the last parameter with a :name key will create a named cycle. You can manually reset a cycle by calling reset_cycle and passing the name of the cycle. 

  <% @items.each do |item| %>
    <tr class="<%= cycle("even", "odd", :name => "row_class")
      <td>
        <% item.values.each do |value| %>
          <span style="color:<%= cycle("red", "green", "blue", :name => "colors") -%>">
            value
          </span>
        <% end %>
        <% reset_cycle("colors") %>
      </td>
   </tr>
 <% end %>

2Notes

Cycle with first and last

georges · Apr 20, 20092 thanks

I needed a cycle that was also aware of the first and last items in the collection. This is adapted from a snippet I found while Googling:

def cycle_with_first_last(object, collection, options = { })
addition = ""
addition += " #{options[:first]}" if object == collection.first
addition += " #{options[:last]}"if object == collection.last
cycle(options[:odd], options[:even]) + addition
end

Just put that in your helpers...

CSS columns

mpearce · Sep 11, 20081 thank

You can also use this in a partial to create blocks of content into columns without setting a fixed height. This one is two columns.

.clear { clear: both;}
.block { float:left;width:200px;}

<div class="block">
<p>Content Item</p>
</div>
<%= cycle("", "<div class=\\"clear\\"></div>") -%>