tput">shared_ptr</code>s to
      all of a slot's tracked objects prior to invoking the slot.  This
      insures none of the tracked objects destruct in mid-invocation.
    </p>
<p>The new connection management scheme has the advantage of being
      non-intrusive.  Objects of any type may be tracked using the
      <code class="computeroutput">shared_ptr</code>/<code class="computeroutput">weak_ptr</code> scheme.  The old
      <code class="computeroutput">boost::signals::trackable</code>
      scheme req