title: How do I dereference a Perl hash reference that's been passed to a subroutine?
body: <p>I'm still trying to sort out my hash dereferencing.  My current problem is I am now passing a hashref to a sub, and I want to dereference it within that sub.  But I'm not finding the correct method/syntax to do it.  Within the sub, I want to iterate the hash keys, but the syntax for a hashref is not the same as a hash, which I know how to do.</p>
  <p>So what I want is to do this:</p>
  <pre><code>sub foo {
      %parms = @_;
      foreach $keys (key %parms) { # do something };
  }
  </code></pre>
  <p>but with a hashref being passed in instead of a hash.</p>