Hello, sorry if this question is too trivial, but I've got some rather strange problem with using the boost::python type wrapper for the python list. It goes as follows: I've got a very small demo program (say main.cpp). Running it causes a segfault. (The actual project is much larger, of course.) The system I use is a Linux OpenSuse 11.1, with the distribution package python-2.6.0-2.23.1 installed. I manually installed boost 1.44 (because the newer versions didn't quite work with the boost-log package, which is needed for the actual project). Which other information might be helpful? This is the program: ******************************************* #include <iostream> #include <boost/python.hpp> using namespace std; int main() { boost::python::list myList; myList.append("foo"); myList.append("fork"); cerr << "Printing length of list." << endl; cerr << "Length of myList: " << boost::python::len(myList) << endl; // the above line causes a segfault! cerr << "TheList: " << boost::python::extract<string>(myList[0])() << "," << boost::python::extract<string>(myList[1])() << endl; cerr << "Finished" << endl; } ******************************************* which I compile by the two commands: /usr/bin/c++ -O0 -Wall -g -I. -I/usr/include/python2.6 -I/usr/local/include -o main.o -c main.cpp /usr/bin/c++ -O0 -Wall -g main.o -o boost_list_test -rdynamic -L/usr/local/lib /usr/local/lib/libboost_python.so -lpython2.6 -Wl,-rpath,/usr/local/lib The segfault occurs at the call to boost::python::len(myList). I debugged the program with gdb, but the backtrace #0 0xb7ec6027 in PyErr_Occurred () from /usr/lib/libpython2.6.so.1.0 #1 0x0804b0b1 in main () at main.cpp:15 doesn't really tell me anything. Interestingly, removing the offending line causes a segfault at the *next* line, with a more verbose backtrace: #0 0xb7e529d7 in PyInt_FromLong () from /usr/lib/libpython2.6.so.1.0 #1 0x0804ba33 in arg_to_python (this=0xbfffee70, x=@0xbfffef48) at /usr/local/include/boost/python/converter/builtin_converters.hpp:122 #2 0x0804ba5d in boost::python::api::object_initializer_impl<false, false>::get<int> (x=@0xbfffef48) at /usr/local/include/boost/python/object_core.hpp:393 #3 0x0804ba9e in boost::python::api::object_base_initializer<int> (x=@0xbfffef48) at /usr/local/include/boost/python/object_core.hpp:315 #4 0x0804bab1 in object<int> (this=0xbfffeedc, x=@0xbfffef48) at /usr/local/include/boost/python/object_core.hpp:334 #5 0x0804bae1 in boost::python::api::object_operators<boost::python::api::object>::operator[]<int> (this=0xbfffef28, key=@0xbfffef48) at /usr/local/include/boost/python/object_items.hpp:61 #6 0x0804af46 in main () at main.cpp:17 I really don't understand what I'm doing wrong. Do I need to resize the list before using append? The documentation (http://www.boost.org/doc/libs/1_44_0/libs/python/doc/v2/list.html) doesn't say anything about this. Any tips or hints are greatly appreciated! Thankyou, - Michael Wand