nvoking 
<code style="white-space: normal">BOOST_CLASS_EXPORT_IMPLEMENT(T)</code>
in the file which defines (implements) the class T.
This ensures that code for the derived class T will
be explicity instantiated.
<li> There needs to be some sort of identifier which can
be used to select the code to be invoked when the object
is loaded.
Standard C++ does implement <code style="white-space: normal">typeid()</code> which can be
used to return a unique string for the class.  This is not entirely
statisfactory f