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June 2020

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Boost Python issue with converters - static linking
by Dominik Cirmirakis June 24, 2020

June 24, 2020

Hi, I have a question regarding the below code. It's an example how to pass a custom class via shared_ptr to embedded python code and it works when boost is dynamically linked. Unfortunately the same code with statically linked boost doesn't work with the following error message: "No to_python (by-value) converter found for C++ type: class boost::shared_ptr<class Foo>". I don't understand why a different linking can affect type recognition of a registered converter. What am I missing? Can anybody help me out? Thanks, Dominik https://stackoverflow.com/questions/8225934/exposing-a-c-class-instance-to-… #include <boost/shared_ptr.hpp> #include <boost/make_shared.hpp> #include <boost/python.hpp> #include <string> #include <iostream> namespace bp = boost::python; struct Foo{ Foo(){} Foo(std::string const& s) : m_string(s){} void doSomething() { std::cout << "Foo:" << m_string << std::endl; } std::string m_string; }; typedef boost::shared_ptr<Foo> foo_ptr; BOOST_PYTHON_MODULE(hello) { bp::class_<Foo, foo_ptr>("Foo") .def("doSomething", &Foo::doSomething) ; }; int main(int argc, char **argv) { Py_Initialize(); try { PyRun_SimpleString( "a_foo = None\n" "\n" "def setup(a_foo_from_cxx):\n" " print 'setup called with', a_foo_from_cxx\n" " global a_foo\n" " a_foo = a_foo_from_cxx\n" "\n" "def run():\n" " a_foo.doSomething()\n" "\n" "print 'main module loaded'\n" ); foo_ptr a_cxx_foo = boost::make_shared<Foo>("c++"); inithello(); bp::object main = bp::object(bp::handle<>(bp::borrowed( PyImport_AddModule("__main__") ))); // pass the reference to a_cxx_foo into python: bp::object setup_func = main.attr("setup"); setup_func(a_cxx_foo); // now run the python 'main' function bp::object run_func = main.attr("run"); run_func(); } catch (bp::error_already_set) { PyErr_Print(); } Py_Finalize(); return 0; }

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Boost class to represent PyBytesObject ?
by Alain O' Miniussi June 11, 2020

June 11, 2020

Hi, The pickle API has changed between Python 2 and 3, moving from str (represented by the boost::python::str class) to bytes. For serialization purpose, I need to represent the Python's bytes (PyBytesObject in C) type in C++. What would be the the best type to extract<waht?> to ? Thank ---- Alain Miniussi DSI, Pôles Calcul et Genie Log. Observatoire de la Côte d'Azur Tél. : +33492003009 (Mont-Gros) +33483618544 (Sophia Antipolis) +33609650665

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