BPL support for exporting/importing class wrappers.

[SVN r8788]

example/abstract.cpp

@@ -0,0 +1,34 @@
+// Example by Ullrich Koethe
+#include "boost/python/class_builder.hpp"
+#include <string>
+
+struct Abstract
+{
+    virtual std::string test() = 0;
+};
+
+struct Abstract_callback: Abstract
+{
+    Abstract_callback(PyObject * self)
+    : m_self(self)
+    {}
+
+    std::string test()
+    {
+      return boost::python::callback<std::string>::call_method(m_self, "test");
+    }
+
+    PyObject * m_self;
+};
+
+extern "C"
+DL_EXPORT(void)
+initabstract()
+{
+    boost::python::module_builder a("abstract");
+
+    boost::python::class_builder<Abstract, Abstract_callback>
+        a_class(a, "Abstract");
+    a_class.def(boost::python::constructor<>()); // wrap a constructor
+    a_class.def(&Abstract::test, "test");
+}