array_floe

This small extension to ruby's Array class simplifies the reasonably-common need to specially handle "floe"--i.e., first, last, odd, even--when iterating through the elements of an array. It's particularly handy for generating CSS classes.

Full Rdoc is available at http://rubydoc.info/gems/array_floe

Usage

The gem provides two additional iterators, Array#each_with_floe and Array#each_with_index_floe, that provide a "floe" object for each element in the array:

ary.each_with_floe do |element, floe|
    if floe.first?
        puts "#{element} is the first element"
    end
    if floe.last?
        puts "#{element} is the last element"
    end
    if floe.odd?
        puts "#{element} is an odd-numbered element"
    end
    if floe.even?
        puts "#{element} is an even-numbered element"
    end
end

ary.each_with_index_floe do |element, i, floe|
    assert_equal(i == 0,          floe.first?)
    assert_equal(i == ary.size-1, floe.last?)
    assert_equal(i % 2 == 1,      float.odd?)
    assert_equal(i % 2 == 0,      float.even?)
end

If no block is given, an enumerator is returned instead.

The "floe" object's to_s method returns a space-separated list of "first", "last", "odd", and "even" as appropriate:

[:a, :b, :c, :d].each_with_floe.collect{|element, floe| floe.to_s} #=> [ "first even", "odd", "even", "last odd" ]

floe.to_s is particularly useful to construct CSS classes when generating HTML. For example, this haml snippet:

%table
- [:a, :b, :c, :d].each_with_floe do |row, floe|
  %tr{:class => floe}
    %td= row

would yield this HTML snippet:

<table>
    <tr class="first even">
        <td>a</td>
    </tr>
    <tr class="odd">
        <td>b</td>
    </tr>
    <tr class="even">
        <td>c</td>
    </tr>
    <tr class="last odd">
        <td>d</td>
    </tr>
</table>

Installing

Standard installation from http://rubygems.org/gems/array_floe

% gem install array_floe

or, if you're using bundler, include this line in your Gemfile:

gem "array_floe"

Ruby Versions

Tested on ruby 1.8.7 and 1.9.3 and 2.0.0

Copyright

Released under the MIT License. See LICENSE.txt for further details.