title: Why catch an exception as reference-to-const?
body: <p>I've heard and read many times that it is better to catch an exception as reference-to-const rather than as reference. Why is:</p>
  
  <pre><code>try {
      // stuff
  } catch (const std::exception&amp; e) {
      // stuff
  }
  </code></pre>
  
  <p>better than:</p>
  
  <pre><code>try {
      // stuff
  } catch (std::exception&amp; e) {
      // stuff
  }
  </code></pre>