title: perl -w VS use warnings
body: <p>We had some discussion on perl coding standards, one is about using</p>
  
  <pre><code>perl -w
  </code></pre>
  
  <p>or </p>
  
  <pre><code>use warnings
  </code></pre>
  
  <p>Some prefer the later one because of below reasons:</p>
  
  <ol>
  <li>use warnings can be applied selectively </li>
  <li>categories of warnings can be enabled and disabled (-w is either completely on or off)</li>
  </ol>
  
  <p>How do you think?</p>