[Boost-bugs] [Boost C++ Libraries] #2049: extracting c++ pointer from python object with multiple parents

Subject: [Boost-bugs] [Boost C++ Libraries] #2049: extracting c++ pointer from python object with multiple parents
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2008-06-25 15:50:06

#2049: extracting c++ pointer from python object with multiple parents
----------------------------------+-----------------------------------------
 Reporter:  bloodyfanatic_at_[hidden]  |       Owner:  dave   
     Type:  Bugs                  |      Status:  new    
Milestone:  Boost 1.35.1          |   Component:  Python 
  Version:  Boost 1.35.0          |    Severity:  Problem
 Keywords:                        |  
----------------------------------+-----------------------------------------
 Extracting a C++ pointer from a python object which inherited two base
 classes form C++ doesn't work correctly.
 Only the first base can be extracted, the second cannot be extracted under
 all circumstances.
 The script runs within an embedded python interpreter.

 CPP code:

 {{{
 #define BOOST_PYTHON_STATIC_LIB
 #include <boost/python.hpp>

 using namespace boost::python;

 class Base1
 {
 public:
         virtual ~Base1() {}
 };

 class Base2
 {
 public:
         virtual ~Base2() {}
 };


 void extractBase1( boost::python::object& obj)
 {
         Base1* ex1 = extract<Base1*>(obj) BOOST_EXTRACT_WORKAROUND;
         Base1& ex2 = extract<Base1&>(obj) BOOST_EXTRACT_WORKAROUND;
 }

 void extractBase2( boost::python::object& obj)
 {
         Base2* ex1 = extract<Base2*>(obj) BOOST_EXTRACT_WORKAROUND;
         Base2& ex2 = extract<Base2&>(obj) BOOST_EXTRACT_WORKAROUND;
 }


 BOOST_PYTHON_MODULE(Test_ext)
 {
         class_<Base1, boost::noncopyable>("Base1");
         class_<Base2, boost::noncopyable>("Base2");

         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 );
         }
         catch (error_already_set)
         {
                 PyErr_Print();
         }

         return 0;
 }
 }}}

 test.py:

 {{{

 from Test_ext import *

 class both1(Base1, Base2):
         def foo(self):
                 print "foo!"

 class both2(Base2, Base1):
         def foo(self):
                 print "foo2!"

 obj1 = both1()

 extractBase1(obj1)
 extractBase2(obj1)      # doesn't work

 obj2 = both()

 extractBase1(obj2)      # doesn't work
 extractBase2(obj2)
 }}}

-- 
Ticket URL: <http://svn.boost.org/trac/boost/ticket/2049>
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