>Derived</tt>. In such cases, we use

<tt>return_value_policy&lt;manage_new_object&gt;</tt> to instruct Python to adopt

the pointer to <tt>Base</tt> and hold the instance in a new Python <tt>Base</tt>

object until the the Python object is destroyed. We shall see more of

Boost.Python <a href="call_policies.html">

call policies</a> later.</p>

<code><pre>

    <span class=comment>// Tell Python to take ownership of factory's result

    </span><span class=identifier>def</span><span class=special>(