title: { } mark in echo "{$e->getMessage()}"
body: <p>I read about this <a href="http://net.tutsplus.com/tutorials/php/the-ins-and-outs-of-php-exceptions/comment-page-1/" rel="noreferrer">Article</a> 
  I wondering about this part: </p>
  
  <pre><code>try {
      //First try getting our user numero uno
      $user = new User(1);
  
      //Then, let's try to get the exception
      $user2 = new User('not numeric');
  } catch( Exception $e ) {
      echo "Donkey Kong has caught an exception: {$e-&gt;getMessage()}";
  }
  </code></pre>
  
  <p>why <code>{$e-&gt;getMessage()}</code> must be covered in bracket?<br>
  Is there any link explanation on php manual about this?</p>
  
  <p>i know if we don't put bracket it will show error, but want i want is to get the explanation why bracket is needed.</p>
  
  <blockquote>
    <p>Notice: Undefined property: Exception::$getMessage</p>
  </blockquote>