title: Time difference respecting day light savings
body: <p>I have two <code>long</code>s representing time since the epoch. They both have the same timezone. I want to find the difference <strong>in seconds</strong> between these two times, respecting day light savings.</p>
  
  <pre><code>(def a (java.util.Date. 1259568796000))  ;; Before Day Light Savings
  
  (def b (java.util.Date. 1255147200000))  ;; After Day Light Savings
  </code></pre>
  
  <p>Where 'a' is <code>2009-11-30T08:13:16.000-00:00</code></p>
  
  <p>and</p>
  
  <p>Where 'b' is <code>2009-10-10T04:00:00.000-00:00</code></p>
  
  <p>Using JodaTime, I can make an <code>Interval</code> out of these two times, turn them into a <code>Duration</code>, and get the <code>StandardSeconds</code>.</p>
  
  <pre><code>(.getStandardSeconds (.toDuration (Interval. a b)))
  </code></pre>
  
  <p>This doesn't work though, because the docs for <code>Period</code> indicate that <code>Duration</code> will mess up Day Light Savings:</p>
  
  <blockquote>
    <p>When this time period is added to an instant, the effect is of adding
    each field in turn. As a result, this takes into account daylight
    savings time. Adding a time period of 1 day to the day before daylight
    savings starts will only add 23 hours rather than 24 to ensure that
    the time remains the same. If this is not the behaviour you want, then
    see Duration.</p>
  </blockquote>
  
  <p>How can I accomplish this task?</p>