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April 2014

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boost::python embedding error - runtime - Mac OS X - 1.38
by Igor Karpov Oct. 1, 2014

Oct. 1, 2014

Hi, I am trying to run the following program: #include <iostream> #include <Python.h> #include <boost/python.hpp> using namespace boost::python; using namespace std; int main(int argc, char** argv) { { // Using Python/C Py_Initialize(); PyObject* main_module = PyImport_ImportModule("__main__"); PyObject* globals = PyEval_GetGlobals(); PyObject* locals = PyEval_GetLocals(); PyRun_SimpleString("print 'Hello World, from Python/C!'\n"); Py_Finalize(); } { // Using boost::python Py_Initialize(); object main_module = import("__main__"); object main_namespace = main_module.attr("__dict__"); try { object ignored = exec("print 'Hello World, from boost::python!'\n", main_namespace); Py_Finalize(); } catch (error_already_set const& e) { PyErr_Print(); return 1; } } return 0; } on Linux (both x86 and x86_64), with Ubuntu's default version of Boost (1.34.1) installed, I am able to do so as expected: $ ./embed Hello World, from Python/C! Hello World, from boost::python! on Mac OS X, I get a runtime error: $ ./embed Hello World, from Python/C! Bus Error Running with gdb, this is the stack trace: Hello World, from Python/C! Program received signal EXC_BAD_ACCESS, Could not access memory. Reason: KERN_PROTECTION_FAILURE at address: 0x00000000 0x00000000 in ?? () (gdb) where #0 0x00000000 in ?? () #1 0x00bb618f in PyEval_GetGlobals () #2 0x00bce0dd in PyImport_Import () #3 0x00bce2b0 in PyImport_ImportModule () #4 0x008127d4 in boost::python::import (name=@0xbffff4a8) at libs/python/src/import.cpp:20 #5 0x00004446 in main (argc=1, argv=0xbffff510) at embed.cc:22 For this Mac, boost version is latest (1.38) and python version is: Python 2.5.4 (r254:67917, Dec 23 2008, 14:57:27) [GCC 4.0.1 (Apple Computer, Inc. build 5363)] on darwin Is this a bug? I attached the source and the cmake file I am using to build, for convenience. Thanks, --Igor.

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Fail to initialize boost::python::object with a class with an overloaded operator&
by Mehdi AMINI April 19, 2014

April 19, 2014

Hi, Possibly related but old: https://mail.python.org/pipermail/cplusplus-sig/2005-October/009304.html Trying to create a boost::python::object with an instance of a class that has a "crazy" operator& fails here: boost/python/converter/arg_to_python.hpp:209:9: error: no matching constructor for initialization of 'boost::python::converter::detail::arg_to_python_base' : arg_to_python_base(&x, registered<T>::converters) Replacing "&x" with "addressof(x)" solve the issue, if you don't see any drawback I suggest it could be changed in the next release :) Note: I know that overloading wildy the operator& is considered as bad, but my sample code seems quite "standard": std::vector<bool> v { true }; boost::python::object b_(v[0]); It fails when compiling with libc++ as they handle (the infamous) std::vector<bool> in a (non standard) way similar as std::bitset and provided a class to wrap reference to element of the vector. This __bit_reference overloads the operator& to return a __bit_iterator, which breaks boost::python::object initialization. The trace is: include/boost/python/converter/arg_to_python.hpp:256:7: note: in instantiation of member function 'boost::python::converter::detail::value_arg_to_python<std::__1::__bit_reference<std::__1::vector<bool, std::__1::allocator<bool> >, true> >::value_arg_to_python' requested here : base(x) ^ include/boost/python/object_core.hpp:393:33: note: in instantiation of member function 'boost::python::converter::arg_to_python<std::__1::__bit_reference<std::__1::vector<bool, std::__1::allocator<bool> >, true> >::arg_to_python' requested here return python::incref(converter::arg_to_python<T>(x).get()); ^ include/boost/python/object_core.hpp:312:10: note: in instantiation of function template specialization 'boost::python::api::object_initializer_impl<false, false>::get<std::__1::__bit_reference<std::__1::vector<bool, std::__1::allocator<bool> >, true> >' requested here >::get( ^ include/boost/python/object_core.hpp:334:23: note: in instantiation of function template specialization 'boost::python::api::object_base_initializer<std::__1::__bit_reference<std::__1::vector<bool, std::__1::allocator<bool> >, true> >' requested here : object_base(object_base_initializer(x)) ^ helloworld.cpp:28:25: note: in instantiation of function template specialization 'boost::python::api::object::object<std::__1::__bit_reference<std::__1::vector<bool, std::__1::allocator<bool> >, true> >' requested here boost::python::object b_(v[0]); ^ include/boost/python/converter/arg_to_python_base.hpp:20:7: note: candidate constructor not viable: no known conversion from '__bit_iterator<std::__1::vector<bool, std::__1::allocator<bool> >, false>' to 'const volatile void *' for 1st argument arg_to_python_base(void const volatile* source, registration const&); ^ Best, Mehdi

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