title: How to set the value of a variable to null in Perl?
body: <p>I found in some examples, the so-called constructor <code>new</code> method contains initialization for the values of properties of a class (package) like this:</p>
  
  <pre><code>my $self = {
      _firstName =&gt; shift,
      _lastName  =&gt; shift,
      _ssn       =&gt; shift,
  };
  </code></pre>
  
  <p>I know that <a href="http://p3rl.org/shift" rel="nofollow">shift</a> is a function, but does the assignment above set the properties to null?</p>