Sorry, there are no things

You know when there's something in the back of your mind, something you want to check out that you never get around to? Here's one from why that just made my day! 

things = [1,2,3] 

if things.each do |thing|
  puts thing
end.empty? then
  puts "no things!"
end

It takes the classic case of if there's things, use the things, otherwise do something completely different and makes it beautiful. This is extra handy in ERB since there's only three lines of logic instead of five. (Note using the for..in alternative as well).

<% if for thing in things %>
  <%= thing %>
  <% end.empty? then %>
    no things
<% end %>

Bonus points for anyone that can write the following more simply...

<% unless things.empty? %>
  <ul>
    <% for thing in things %>
      <li><%= thing %></li>
    <% end %>
  </ul>
<% else %>
  no things
<% end %>
  • April 23, 2005
  • Dealing with ruby

There are 4 comments

  1. 10 days later, andrew said...

    Note that the "then" in your first two examples is extraneous. No help on the third though. :-)

  2. 18 days later, John said...

    Depends on what you consider more simply I guess.

    <%= things.empty? ? 'NO THINGS' : contenttag('ul', things.collect { |thing| contenttag('li', thing) }) %>

  3. 24 days later, Victor said...

    Personally, I find the example a little wordy and obfuscatory. If you expect the block to have side-effects, as in this example, the following is far easier to stuff in ERB:

    puts 'no things' if things.reject {|thing| puts thing}.empty?

  4. 32 days later, tim said...

    @andrew: the 'then' helps with readability - see flgr's comment on the redhanded post

    Assuming the existence of an array helper method, you could do: <%= things.empty?? "no things" : things.to_html %>