title: Variable length look-behind
body: <p>Is there any elegant solution to build a variable length look-behind regex such as this one ? </p>
  
  <pre><code>/(?&lt;=eat_(apple|pear|orange)_)today|yesterday/g;
  </code></pre>
  
  <p>It seems Perl has a very impressive regex engine and variable length lookbehind would be very interesting. Is there a way to make it work or should I forget this bad idea ?</p>