title: Regex to allow alphanumeric and dot
body: <p>Hi I have a variable in a Silex route and we only allow alphanumeric values</p>
  
  <pre><code>-&gt;assert('hash','\w+')
  </code></pre>
  
  <p>I would like to also allow a dot in the variable, but my efforts at editing this regex have failed.  Help greatly appreciated, thanks!</p>