[C++-sig] problem with boost::python::extract of c++ pointers from objects with multiple inheritance

[David Abrahams]

Thank you; could you attach this to a ticket at http://svn.boost.org?

Thanks again!

Sent from my iPhone

On Jun 25, 2008, at 5:17 AM, Carsten Harms <CarstenHarms9368 at gmx.de>  
wrote:

> Here is a small app which reproduces the behaviour:
> --------------------------------------------------
> #define BOOST_PYTHON_STATIC_LIB
> #include <boost/python.hpp>
> #include <iostream>
> #include "conio.h"
>
> using namespace boost::python;
>
> class Base1
> {
> public:
>   virtual ~Base1() {}
>   virtual void func1 () = 0;
> };
>
> class Base1Wrap: public Base1, public wrapper<Base1>
> {
> public:
>   virtual ~Base1Wrap() {}
>   void func1 () {    this->get_override("func1")(); }
> };
>
>
> class Base2
> {
> public:
>   virtual ~Base2() {}
>   virtual void func2 () = 0;
> };
>
> class Base2Wrap: public Base2, public wrapper<Base2>
> {
> public:
>   virtual ~Base2Wrap() {}
>   void func2 () {    this->get_override("func2")(); }
> };
>
>
>
> void extractBase1( boost::python::object& obj)
> {
>   Base1* ex1 = extract<Base1*>(obj) BOOST_EXTRACT_WORKAROUND;
>   Base1& ex2 = extract<Base1&>(obj) BOOST_EXTRACT_WORKAROUND;
>
>   ex1->func1();
>   ex2.func1();
> }
>
> void extractBase2( boost::python::object& obj)
> {
>   Base2* ex1 = extract<Base2*>(obj) BOOST_EXTRACT_WORKAROUND;
>   Base2& ex2 = extract<Base2&>(obj) BOOST_EXTRACT_WORKAROUND;
>
>   ex1->func2();
>   ex2.func2();
> }
>
>
> BOOST_PYTHON_MODULE(Test_ext)
> {
>   class_<Base1Wrap, boost::noncopyable>("Base1")
>       .def("func1", pure_virtual(&Base1::func1))
>       ;
>
>   class_<Base2Wrap, boost::noncopyable>("Base2")
>       .def("func2", pure_virtual(&Base2::func2))
>       ;
>
>   def("extractBase1", extractBase1);
>   def("extractBase2", extractBase2);
> }
>
>
> int main(int, char **)
> {
> try
> {
>     Py_Initialize();
>          initTest_ext();
>
>     object main = import("__main__");
>     object dictionary(main.attr("__dict__"));
>
>     object result = exec_file("test.py", dictionary, dictionary );
>          //Py_Finalize();
> }
> catch (error_already_set)
> {
>     PyErr_Print();
> }
>
> while(!kbhit());
>
> return 0;
> }
> --------------------------------------------------
> python script:
> --------------------------------------------------
>
> from Test_ext import *
>
> class class1(Base1):
>   def func1(self):
>       print "func1 called!"
>      class class2(Base2):
>   def func2(self):
>       print "func2 called!"
>
> class both1(Base1, Base2):
>   def func1(self):
>       print "func1 called!"
>   def func2(self):
>       print "func2 called!"
>      class both2(Base2, Base1):
>   def func1(self):
>       print "func1 called!"
>   def func2(self):
>       print "func2 called!"
>
> #################################
> object1 = class1()
> object2 = class2()
>
> extractBase1(object1)
> extractBase2(object2)
>
>
> object3 = both1()
>
> extractBase1(object3)
> extractBase2(object3)    # doesn't work
>
> object4 = both2()
>
> extractBase1(object4)    # doesn't work
> extractBase2(object4)
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