https://svn.boost.org/trac10/ticket/138 <pre class="wiki">I'm having problems overriding functions in Python with Boost. The examples provided on the website seem to work. However, all the examples I have managed to find have involved callback classes with virtual function overrides having zero arguments. I am trying to override functions with multiple arguments with no success. I get consistent errors when trying to manipulate multi-argument virtual functions polymorphically from a C++ extension. Im currently using Visual Studio .Net and Python 2.2.2. The following code demostrates the problem: ------------------Begin Code --------------------------- C++ code: #include &lt;iostream&gt; #include &lt;string&gt; class Entity { public: Entity() {Class = "Entity"; } Entity(const Entity&amp; e) { this-&gt;Class = e.Class; } std::string virtual GetClass(std::string PreFix) { return Class + PreFix; } public: std::string Class; }; class SimpleEntity : public Entity { public: SimpleEntity() { this-&gt;Class = "SimpleEntity"; } SimpleEntity(const SimpleEntity&amp; se) { this- &gt;Class = se.Class; } std::string virtual GetClass(std::string PreFix) { return Class + PreFix; } }; #include &lt;boost/python/module.hpp&gt; #include &lt;boost/python/def.hpp&gt; #include &lt;boost/python/args.hpp&gt; #include &lt;boost/python/class.hpp&gt; #include &lt;boost/python/overloads.hpp&gt; #include &lt;boost/python/call_method.hpp&gt; using namespace boost::python; std::string Test(Entity* e, std::string PreFix) { return e-&gt;GetClass(PreFix); } class EntityWrap : public Entity { public: EntityWrap(PyObject* self_) : self(self_) {} EntityWrap(PyObject* self_, const Entity&amp; e) : self(self_), Entity(e) {} std::string GetClass(std::string PreFix) { return call_method&lt;std::string&gt;(self, "GetClass", PreFix); } std::string default_GetClass( Entity&amp; e, std::string PreFix) { return e.Entity::GetClass(PreFix); } private: PyObject* self; }; class SimpleEntityWrap : public SimpleEntity { public: SimpleEntityWrap(PyObject* self_) : self(self_) {} SimpleEntityWrap(PyObject* self_, const SimpleEntity&amp; se) : self(self_), SimpleEntity(se) {} std::string GetClass(std::string PreFix) { return call_method&lt;std::string&gt;(self, "GetClass", PreFix); } std::string default_GetClass( SimpleEntity&amp; se, std::string PreFix) { return se.SimpleEntity::GetClass (PreFix); } private: PyObject* self; }; BOOST_PYTHON_MODULE(hello) { class_&lt;Entity, EntityWrap&gt;("Entity") .def(init&lt;const Entity&amp;&gt;()) .def("GetClass", &amp;EntityWrap::default_GetClass) .def_readwrite("Class", &amp;Entity::Class); ; class_&lt;SimpleEntity, SimpleEntityWrap, bases&lt;Entity&gt; &gt;("SimpleEntity") .def(init&lt;const SimpleEntity&amp;&gt;()) .def("GetClass", &amp;SimpleEntityWrap::default_GetClass) ; def("Test", Test); } Python Code: Python 2.2.2 (#37, Oct 14 2002, 17:02:34) [MSC 32 bit (Intel)] on win32 Type "copyright", "credits" or "license" for more information. IDLE 0.8 -- press F1 for help &gt;&gt;&gt; from hello import * &gt;&gt;&gt; class DerivedEntity(SimpleEntity): def __init__(self): SimpleEntity.Class = "DerivedEntity" def GetClass(self,x): return self.Class + x &gt;&gt;&gt; e = Entity() &gt;&gt;&gt; Test(e, " a test") Traceback (most recent call last): File "&lt;pyshell#4&gt;", line 1, in ? Test(e, " a test") TypeError: bad argument type for built-in operation &gt;&gt;&gt; s = SimpleEntity() &gt;&gt;&gt; Test(s, " a test") Traceback (most recent call last): File "&lt;pyshell#6&gt;", line 1, in ? Test(s, " a test") TypeError: bad argument type for built-in operation &gt;&gt;&gt; d = DerivedEntity() &gt;&gt;&gt; Test(d, " a test") Traceback (most recent call last): File "&lt;pyshell#8&gt;", line 1, in ? Test(d, " a test") TypeError: bad argument type for built-in operation &gt;&gt;&gt; e.Class 'Entity' &gt;&gt;&gt; e.GetClass(" a test") Traceback (most recent call last): File "&lt;pyshell#10&gt;", line 1, in ? e.GetClass(" a test") TypeError: bad argument type for built-in operation &gt;&gt;&gt; s.Class 'DerivedEntity' &gt;&gt;&gt; s.GetClass("a test") Traceback (most recent call last): File "&lt;pyshell#12&gt;", line 1, in ? s.GetClass("a test") TypeError: bad argument type for built-in operation &gt;&gt;&gt; d.Class 'DerivedEntity' &gt;&gt;&gt; d.GetClass(" a test") 'DerivedEntity a test' &gt;&gt;&gt; ------------------End Code --------------------------- Am I missing something? Any help would be appreciated. Thanks, Vince </pre> en-us /htdocs/site/boost.png https://svn.boost.org/trac10/ticket/138 Trac 1.4.3 Joel de Guzman Tue, 25 Feb 2003 04:01:54 GMT https://svn.boost.org/trac10/ticket/138#comment:4 https://svn.boost.org/trac10/ticket/138#comment:4 <ul> <li><strong>status</strong> <span class="trac-field-old">assigned</span> → <span class="trac-field-new">closed</span> </li> </ul> Ticket