title: regexp - combine two classes
body: <p>I have a string and want to remove all non-symbolic characters (exclude ' ').  So if I have a "some, - another" I want to get "some  another".</p>
  
  <p>I can use <code>s.gsub(/\W/, '')</code> to remove all non-symbolic characters, but it remove spaces ' ' also.</p>
  
  <p>I can use <code>s.gsub(/\S/, '')</code> to remove all non-spaces, but it removes all symbolic characters.</p>
  
  <p>How can I combine this two conditions?</p>