title: validate dots and comma with regex ruby 1.9.2
body: <p>I have this regex in my model post:</p>
  
  <pre><code>validates_format_of :description, :username, :with =&gt; /^(?:[^\W_]|\s)*$/u, :message =&gt; "should only contain letters, numbers, or .,-_@"
  </code></pre>
  
  <p>But this regex does not allow dots "<strong>.</strong>" and commas "<strong>,</strong>". </p>
  
  <p><strong>I want allow add this characters to this regex.</strong></p>
  
  <p>How can I allow that this regex works fine for fields like <strong>username</strong> or textareas for validate letters, numbers, commas, dots...etc</p>