 Init&gt;
class_&amp; def(Init init_expr);
</pre>

  <dl class="function-semantics">
    <dt><b>Requires:</b> <code>init_expr</code> is the result of an <a href=
    "init.html#init-expressions">init-expression</a> compatible with
    <code>T</code>.</dt>

    <dt><b>Effects:</b> For each <a href="init.html#init-expressions">valid
    prefix</a> <em>P</em> of <code>Init</code>, adds an
    <code>__init__(</code>...<code>)</code> function overload to the
    extension class accepting <em>P</em> as arguments.