Mailman 3 January 2015 - Cplusplus-sig

Boost.Python: Review of Patches
by Huebl, Axel Feb. 12, 2015

Feb. 12, 2015

Hi, I was directed here from the Boost groups homepage http://www.boost.org/community/groups.html#cplussig so I hope my question is well placed. I was wondering if, how and when patches for Boost.Python (specially bug fixes) are merged. When I reported two bugs (including patches) beginning of the month (that sounds a bit impatient - so if I am just pushing to much just tell me) in both trac and on GitHub: https://svn.boost.org/trac/boost/ticket/10932 https://svn.boost.org/trac/boost/ticket/10933 I noticed that there are other pull requests since at least two boost stable releases on GitHub https://github.com/boostorg/python/pulls (some of them also with a trac issue) that have not yet been reviewed/included/commented-on/closed in the code base even if they are most of the time straight forward fixes. My background: I am combined Boost.Python with via cmake with an open source, (mpi) parallel, many-GPGPU code [1] compiled with nvcc 6.5 and noted some minor compile errors in Boost.Python that can be fixed quite easily. (Btw: it works like a charm, thank you so much!) Best regards, Axel Huebl [1] http://picongpu.hzdr.de -- Axel Huebl Phone +49 351 260 3582 https://www.hzdr.de/crp Computational Radiation Physics Laser Particle Acceleration Division Helmholtz-Zentrum Dresden - Rossendorf e.V. Bautzner Landstrasse 400, 01328 Dresden POB 510119, D-01314 Dresden Vorstand: Prof. Dr.Dr.h.c. R. Sauerbrey Prof. Dr.Dr.h.c. P. Joehnk VR 1693 beim Amtsgericht Dresden

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Unicode string in different version of libboost-python
by Vincent Vande Vyvre Jan. 27, 2015

Jan. 27, 2015

Hi, I'm working on a python wrapper for the lib libexiv2 This is the port to Python 3 of pyexiv2 written for Python 2 I've two machines, one 32 bits with these versions: vincent@tiemoko:~$ dpkg --list | grep libboost ii libboost-python-dev 1.48.0.2 Boost.Python Library development files (default version) ii libboost-python1.46-dev 1.46.1-7ubuntu3 Boost.Python Library development files ii libboost-python1.46.1 1.46.1-7ubuntu3 Boost.Python Library ii libboost-python1.48.0 1.48.0-3 Boost.Python Library ii libboost1.46-dev 1.46.1-7ubuntu3 Boost C++ Libraries development files and one 64 bits (this is my main devel machine): vincent@djoliba:~$ dpkg --list | grep libboost ii libboost-date-time1.54.0:amd64 1.54.0-4ubuntu3.1 amd64 set of date-time libraries ii libboost-python-dev 1.54.0.1ubuntu1 amd64 Boost.Python Library ii libboost-python1.54-dev:amd64 1.54.0-4ubuntu3.1 amd64 Boost.Python Library development files ii libboost-python1.54.0:amd64 1.54.0-4ubuntu3.1 amd64 Boost.Python Library rc libboost-serialization1.46.1 1.46.1-7ubuntu3 amd64 serialization library for C++ ii libboost-system1.54.0:amd64 1.54.0-4ubuntu3.1 amd64 Operating system (e.g. diagnostics support) library ii libboost1.54-dev 1.54.0-4ubuntu3.1 amd64 Boost C++ Libraries development files It's seems these different versions have different behaviours with the python string. On the more recent version, I encode my python string in utf-8 before send it to the wrapper and that's works fine. On the 32 bits machine I've this error: TypeError: No registered converter was able to produce a C++ rvalue of type std::string from this Python object of type bytes If I send directly the unicode string to the wrapper, without encoding, that's solve the problem. Example: python: # xmp tag values are embedded into a list value = ['déjà vu'] try: tag._setArrayValue([v.encode('utf-8') for v in value]) except TypeError: # old libboost-python version tag._setArrayValue(value) ------------------------------------------------------------------------- exiv2wrapper_python.cpp #include "exiv2wrapper.hpp" #include "exiv2/exv_conf.h" #include "exiv2/version.hpp" #include <boost/python.hpp> using namespace boost::python; using namespace exiv2wrapper; BOOST_PYTHON_MODULE(libexiv2python) { scope().attr("exiv2_version_info") = \ boost::python::make_tuple(EXIV2_MAJOR_VERSION, EXIV2_MINOR_VERSION, EXIV2_PATCH_VERSION); register_exception_translator<Exiv2::Error>(&translateExiv2Error); // Swallow all warnings and error messages written by libexiv2 to stderr // (if it was compiled with DEBUG or without SUPPRESS_WARNINGS). // See https://bugs.launchpad.net/pyexiv2/+bug/507620. std::cerr.rdbuf(NULL); [skip] .def("_setArrayValue", &XmpTag::setArrayValue) --------------------------------------------------------------------------- exiv2wrapper.cpp #include "exiv2wrapper.hpp" #include "boost/python/stl_iterator.hpp" #include <fstream> [skip] void XmpTag::setArrayValue(const boost::python::list& values) { // Reset the value _datum->setValue(0); for(boost::python::stl_input_iterator<std::string> iterator(values); iterator != boost::python::stl_input_iterator<std::string>(); ++iterator) { _datum->setValue(*iterator); } } ------------------------------------------------------------------------- Is this difference into two versions is normal ? I can adapt my python code for that, but how to know the version of libboost ? Here I use "dpkg --list | grep libboost" but that's for debian pacckaging system only and my lib must be run on any os (Windows include). Thanks for all advices. Vincent

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[Boost Python] Cannot call base method from within python extended class method
by Tiago Coutinho Jan. 13, 2015

Jan. 13, 2015

Hello, My problem is the following: I am trying to bind a third party C++ library to python using boost-python. This library has a class Element and a class Owner (the later takes ownership of an Element object). To make things interesting, Element defines a pure virtual method "get_float". The Element should be sub-classed in python. Here is a simplified version of the library: // m1.hpp --------------------------------------------------------------------- // m1.hpp class Element { public: int get_int() { return -1; } virtual float get_float() = 0; }; class Owner { Element *m_element; public: Owner(): m_element(NULL) {} ~Owner() { delete m_element; } void set_element(Element* e) { delete m_element; m_element = e; }; Element* get_element() { return m_element; } }; and here is how I am binding to python: // m1_py.cpp ---------------------------------------------------------------- class ElementWrap : public Element, public wrapper<Element> { public: PyObject* self; ElementWrap(PyObject* self_): Element(), self(self_) { Py_INCREF(self); } ~ElementWrap() { Py_DECREF(self); } virtual float get_float() { return call_method<float>(self, "get_float"); } }; void set_element(Owner& owner, auto_ptr<Element> e) { owner.set_element(e.get()); e.release(); } BOOST_PYTHON_MODULE(m1) { class_<Element, auto_ptr<ElementWrap>, boost::noncopyable>("Element", init<>()) .def("get_int", &Element::get_int) .def("get_float", &Element::get_float) ; register_ptr_to_python<auto_ptr<Element> >(); implicitly_convertible<auto_ptr<ElementWrap>, auto_ptr<Element> >(); class_<Owner>("Owner", init<>()) .def("set_element", &set_element) .def("get_element", &Owner::get_element, return_internal_reference<>()) ; } ... but when I use it like this: # m2.py ----------------------------------------------------------------------- import m1 class SubElement(m1.Element): def get_float(self): return 4.5678 + self.get_int() element = SubElement() owner = m1.Owner() owner.set_element(element) element = owner.get_element() # ops! print (element.get_float()) I get an exception in the last line: Traceback (most recent call last): File "m2.py", line 16, in <module> print (element.get_float()) File "m2.py", line 8, in get_float return 1.0 + self.get_int() Boost.Python.ArgumentError: Python argument types in Element.get_int(SubElement) did not match C++ signature: get_int(Element {lvalue}) It seems that when I passed ownership to python I lost the ability to call a method from the base class. Can anyone help me? Thanks in advance Cheers Tiago

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boost python wrapping boost message queue problem
by 袁振飞 Jan. 9, 2015

Jan. 9, 2015

Hi all. I wrapped the boost ipc message queue into Python using Boost.Python. Everything goes fine except I found that 1. the try_receive / try_send will block python when the mq is empty / full. 2. when I use the wrapped message queue in one Python thread, any other Python thread would be blocked and won't execute. I'd appreciate a lot for your help! Below is my C++ wrapping codes. =============================================== class message_queue { public: message_queue(unsigned int, const char*, size_t, size_t); ~message_queue(); void send(boost::python::str str_buffer, size_t m_size); void try_send(boost::python::str str_buffer, size_t m_size); boost::python::str receive(size_t m_size); boost::python::str try_receive(size_t m_size); private: bi::message_queue* p_message_queue; }; message_queue::message_queue(unsigned int flag, const char* mq_name, size_t mq_length = 1, size_t m_size = 1) { switch(flag) { case 0: p_message_queue = new bi::message_queue(bi::create_only, mq_name, mq_length, m_size); break; case 1: p_message_queue = new bi::message_queue(bi::open_or_create, mq_name, mq_length, m_size); break; case 2: p_message_queue = new bi::message_queue(bi::open_only, mq_name); break; } } message_queue::~message_queue() { delete p_message_queue; } void message_queue::send(boost::python::str str_buffer, size_t m_size) { assert(m_size == boost::python::extract<size_t>(str_buffer.attr("__len__")())); const char* buffer = boost::python::extract<const char*>(str_buffer); p_message_queue->send(buffer, m_size, 0); } void message_queue::try_send(boost::python::str str_buffer, size_t m_size) { assert(m_size == boost::python::extract<size_t>(str_buffer.attr("__len__")())); const char* buffer = boost::python::extract<const char*>(str_buffer); p_message_queue->try_send(buffer, m_size, 0); return; } boost::python::str message_queue::receive(size_t m_size) { char* buffer = new char[m_size]; bi::message_queue::size_type recvd_size; unsigned int priority; p_message_queue->receive(buffer, m_size, recvd_size, priority); return boost::python::str(buffer, m_size); } boost::python::str message_queue::try_receive(size_t m_size) { char* buffer = new char[m_size]; bi::message_queue::size_type recvd_size; unsigned int priority; p_message_queue->try_receive(buffer, m_size, recvd_size, priority); return boost::python::str(buffer, m_size); } bool shared_memory_object_remove(const char* shm_name) { return bi::shared_memory_object::remove(shm_name); } BOOST_PYTHON_MODULE(boost_ipc) { using namespace boost::python; class_<message_queue>("message_queue", init<unsigned int, const char*, optional<size_t, size_t> >()) .def("send", &message_queue::send) .def("receive", &message_queue::receive) .def("try_send", &message_queue::send) .def("try_receive", &message_queue::receive); def("message_queue_remove", message_queue_remove); scope().attr("O_CREATE_ONLY") = 0; scope().attr("O_OPEN_OR_CREATE") = 1; scope().attr("O_OPEN_ONLY") = 2; } =========================================== Below is the Python Script that will block on try_receive function. =========================================== #!/usr/bin/python import boost_ipc boost_ipc.message_queue_remove("test_mq") mq1 = boost_ipc.message_queue(boost_ipc.O_CREATE_ONLY, "test_mq", 1, 5) mq2 = boost_ipc.message_queue(boost_ipc.O_OPEN_ONLY, "test_mq") mq1.try_send("hello", 5) print mq2.receive(5) print mq2.try_receive(5)

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