title: What does %{} do in Ruby?
body: <p>In Matt's post about <a href="http://blog.mattwynne.net/2008/11/14/dry-up-your-cucumber-steps/" rel="noreferrer">drying up cucumber tests</a>, <a href="http://blog.mattwynne.net/2008/11/14/dry-up-your-cucumber-steps/#comment-411" rel="noreferrer">Aslak suggests</a> the following.</p>
  <blockquote>
  <p>When I have lots of quotes, I prefer this:</p>
  <p>Given %{I enter “#{User.first.username}” in “username”}</p>
  </blockquote>
  <p>What is the <code>%{CONTENT}</code> construct called? Will someone mind referencing it in some documentation? I'm not sure how to go about looking it up.</p>
  <p>There's also the stuff about <code>%Q</code>. Is that equivalent to just <code>%</code>? What of the curly braces? Can you use square braces? Do they function differently?</p>
  <p>Finally, what is the <code>#{&lt;ruby stuff to be evaluated&gt;}</code> construct called? Is there a reference to that in documentation somewhere, too?</p>