Mailman 3 November 2015 - Cplusplus-sig

Boost Python in dynamic libraries
by Slide Nov. 25, 2015

Nov. 25, 2015

I have a set of plugins that I am loading from shared libraries on Linux. I thought I would want to call the initModule function when loading the library, but I am getting the following error when I do so: Fatal Python error: PyThreadState_Get: no current thread Aborted (core dumped) Can anyone point me to an example of something like this? I am using BOOST_PYTHON_MODULE in my shared libraries and then loading them at runtime. I would like to import that module into my main namespace where most of my code is being run. Thanks! slide

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Compilation (?) Problem with boost.python
by Michael Chang Nov. 23, 2015

Nov. 23, 2015

Hello, I am running boost_1_59_0 on Ubuntu, and I bootstrapped/installed (using b2) boost.python without any errors. When I run the quick start example, I get the following error: chachang@chachang-Lenovo-Y50-70:~/Desktop/thesis/VeriFlow-v0.3/boost_1_59_0/libs/python/example/quickstart$ bjam toolset=gcc --verbose-test test warning: mismatched versions of Boost.Build engine and core warning: Boost.Build engine (bjam) is 2011.12.01 warning: Boost.Build core (at /home/chachang/Desktop/thesis/VeriFlow-v0.3/boost_1_59_0/tools/build/src) is 2015.07-git Performing configuration checks - 32-bit : no - 64-bit : yes - arm : no - mips1 : no - power : no - sparc : no - x86 : yes - symlinks supported : yes */home/chachang/Desktop/thesis/VeriFlow-v0.3/boost_1_59_0/tools/build/src/tools/link.jam:398: in link-recursively* *ERROR: rule "READLINK" unknown in module "link".* /home/chachang/Desktop/thesis/VeriFlow-v0.3/boost_1_59_0/tools/build/src/tools/link.jam:472: in link.do-link-recursively /home/chachang/Desktop/thesis/VeriFlow-v0.3/boost_1_59_0/tools/build/src/kernel/modules.jam:107: in modules.call-in /home/chachang/Desktop/thesis/VeriFlow-v0.3/boost_1_59_0/tools/build/src/util/indirect.jam:98: in indirect.call /home/chachang/Desktop/thesis/VeriFlow-v0.3/boost_1_59_0/tools/build/src/build/virtual-target.jam:798: in class(a)action.actualize /home/chachang/Desktop/thesis/VeriFlow-v0.3/boost_1_59_0/tools/build/src/build/virtual-target.jam:311: in actualize-action /home/chachang/Desktop/thesis/VeriFlow-v0.3/boost_1_59_0/tools/build/src/build/virtual-target.jam:497: in actualize-no-scanner /home/chachang/Desktop/thesis/VeriFlow-v0.3/boost_1_59_0/tools/build/src/build/virtual-target.jam:134: in class(a)virtual-target.actualize /home/chachang/Desktop/thesis/VeriFlow-v0.3/boost_1_59_0/tools/build/src/build/virtual-target.jam:855: in actualize-sources /home/chachang/Desktop/thesis/VeriFlow-v0.3/boost_1_59_0/tools/build/src/build/virtual-target.jam:780: in class(a)action.actualize /home/chachang/Desktop/thesis/VeriFlow-v0.3/boost_1_59_0/tools/build/src/build/virtual-target.jam:311: in actualize-action /home/chachang/Desktop/thesis/VeriFlow-v0.3/boost_1_59_0/tools/build/src/build/virtual-target.jam:497: in actualize-no-scanner /home/chachang/Desktop/thesis/VeriFlow-v0.3/boost_1_59_0/tools/build/src/build/virtual-target.jam:134: in class(a)virtual-target.actualize /home/chachang/Desktop/thesis/VeriFlow-v0.3/boost_1_59_0/tools/build/src/build/virtual-target.jam:819: in actualize-source-type /home/chachang/Desktop/thesis/VeriFlow-v0.3/boost_1_59_0/tools/build/src/build/virtual-target.jam:840: in actualize-sources /home/chachang/Desktop/thesis/VeriFlow-v0.3/boost_1_59_0/tools/build/src/build/virtual-target.jam:780: in class(a)action.actualize /home/chachang/Desktop/thesis/VeriFlow-v0.3/boost_1_59_0/tools/build/src/build/virtual-target.jam:311: in actualize-action /home/chachang/Desktop/thesis/VeriFlow-v0.3/boost_1_59_0/tools/build/src/build/virtual-target.jam:497: in actualize-no-scanner /home/chachang/Desktop/thesis/VeriFlow-v0.3/boost_1_59_0/tools/build/src/build/virtual-target.jam:134: in class(a)virtual-target.actualize /home/chachang/Desktop/thesis/VeriFlow-v0.3/boost_1_59_0/tools/build/src/build/virtual-target.jam:819: in actualize-source-type /home/chachang/Desktop/thesis/VeriFlow-v0.3/boost_1_59_0/tools/build/src/build/virtual-target.jam:840: in actualize-sources /home/chachang/Desktop/thesis/VeriFlow-v0.3/boost_1_59_0/tools/build/src/build/virtual-target.jam:780: in class(a)action.actualize /home/chachang/Desktop/thesis/VeriFlow-v0.3/boost_1_59_0/tools/build/src/build/virtual-target.jam:311: in actualize-action /home/chachang/Desktop/thesis/VeriFlow-v0.3/boost_1_59_0/tools/build/src/build/virtual-target.jam:497: in actualize-no-scanner /home/chachang/Desktop/thesis/VeriFlow-v0.3/boost_1_59_0/tools/build/src/build/virtual-target.jam:134: in class(a)virtual-target.actualize /home/chachang/Desktop/thesis/VeriFlow-v0.3/boost_1_59_0/tools/build/src/build/virtual-target.jam:819: in actualize-source-type /home/chachang/Desktop/thesis/VeriFlow-v0.3/boost_1_59_0/tools/build/src/build/virtual-target.jam:840: in actualize-sources /home/chachang/Desktop/thesis/VeriFlow-v0.3/boost_1_59_0/tools/build/src/build/virtual-target.jam:780: in class(a)action.actualize /home/chachang/Desktop/thesis/VeriFlow-v0.3/boost_1_59_0/tools/build/src/build/virtual-target.jam:311: in actualize-action /home/chachang/Desktop/thesis/VeriFlow-v0.3/boost_1_59_0/tools/build/src/build/virtual-target.jam:497: in actualize-no-scanner /home/chachang/Desktop/thesis/VeriFlow-v0.3/boost_1_59_0/tools/build/src/build/virtual-target.jam:134: in class(a)virtual-target.actualize /home/chachang/Desktop/thesis/VeriFlow-v0.3/boost_1_59_0/tools/build/src/build-system.jam:720: in load /home/chachang/Desktop/thesis/VeriFlow-v0.3/boost_1_59_0/libs/python/example/quickstart/../../../../tools/build/src/kernel/modules.jam:295: in import /home/chachang/Desktop/thesis/VeriFlow-v0.3/boost_1_59_0/libs/python/example/quickstart/../../../../tools/build/src/kernel/bootstrap.jam:139: in boost-build /home/chachang/Desktop/thesis/VeriFlow-v0.3/boost_1_59_0/libs/python/example/quickstart/boost-build.jam:7: in module scope Is there any insight to what could be causing this problem? I have installed Boost at local prefix (not /usr/local/); where can I specify the non-default prefix when I run/compile the code? Thanks! Michael Alan Chang Princeton University '16 Computer Science

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C++ comments to docstrings
by Andy Falanga (afalanga) Nov. 19, 2015

Nov. 19, 2015

Hello, My team produces a C++ library exported to python via Boost.Python. We've documented our functions and classes with C#-ish style comments. These are parse-able by Visual Studio and XML files are built from them. When our shared object file is imported in python, a function opens these files and makes the association of the appropriate "docstring" in the XML file with the __doc__ property at runtime. Now that you know how we do it currently, I'd like to know are there better methods in use by, or known to, those in this list? The main hurdle to overcome at this point is that our library is built for both Windows and Linux. Because the documentation method has been to use Visual Studio to build the XML, the Windows build must be done first and the XML left in some place that the Linux build can reach. I'd like to eliminate this dependency for Linux. Andy

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Expose a C++ function with an argument of template vector to Python: Boost.Python.ArgumentError
by Zhan Li Nov. 4, 2015

Nov. 4, 2015

Greetings, I'm new to Boost.Python. I have a C++ library (written and shipped by another party) that I want to wrap into Python modules so that I can use several functions in Python. One function takes an argument that is a C++ template vector. How can I export this function to a python function? In a nutshell, here is what I'm doing now but without luck. I wrap the template vector into a Python class using Boost.Python's vector_indexing_suite. Then in the Python script, I first declare this Python class and then pass it to the function. But I got no luck and the following error message, " Boost.Python.ArgumentError: Python argument types in canupo.read_msc_header(MSCFile, FloatVec, int) did not match C++ signature: read_msc_header(MSCFile {lvalue}, std::vector<float, std::allocator<float> > {lvalue}, int {lvalue}) " More specifically, here are the C++ code and Python script I have. In the C++ library code file "helper.hpp", it has a struct MSCFile and a function read_msc_header. struct MSCFile { // definition of MSCFile }; int read_msc_header(MSCFile& mscfile, std::vector<FloatType>& scales, int& ptn) { // implementation of read_msc_header } The "FloatType" is just a alias for float. In the C++ wrapper code file "wrapper.cpp" #include "helpers.hpp" #include <boost/python.hpp> #include <boost/python/module.hpp> #include <boost/python/def.hpp> #include <boost/python/implicit.hpp> #include <boost/python/suite/indexing/vector_indexing_suite.hpp> BOOST_PYTHON_MODULE(canupo) { using namespace boost::python; class_<std::vector<FloatType> >("FloatVec") .def(vector_indexing_suite<std::vector<FloatType> >()) ; class_<MSCFile>("MSCFile", init<const char*>()) ; def("read_msc_header", read_msc_header); } In the python script, I tried to use the function as following but failed. import canupo mscfile = canupo.MSCFile("msc_file_name") scales = canupo.FloatVec() ptnparams = 0 print canupo.read_msc_header(mscfile, scales, ptnparams) And the error goes like this: Boost.Python.ArgumentError: Python argument types in canupo.read_msc_header(MSCFile, FloatVec, int) did not match C++ signature: read_msc_header(MSCFile {lvalue}, std::vector<float, std::allocator<float> > {lvalue}, int {lvalue}) I googled around but didn't find a good solution or a solution that I can understand well. Most requires rewrite the function with Boost.Python. But I don't want to change the C++ library code itself. I think there may be a good way to expose such a function to Python. Thanks a lot! Zhan. -- Zhan Li, 李展; Earth & Environment, Boston University, USA; 2008 - 2011, in Chinese Academy of Sciences, China; 2004 - 2008, in Nanjing University, China;

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Accessing pointer properties with boost-python ?
by Vivien Henry Nov. 1, 2015

Nov. 1, 2015

Hello everyone, I am new on this mailing-list, so; first, My name is Vivien Henry, working as Electrical Engineer in France I am currently trying to wrap a CAD software, gerbv (http://gerbv.geda-project.org/), which is designed to handle Gerber files. (They also provide it as a library) the file wrapper.cpp is generated through a personal script The script is still a work in progress. The generated code compiles, creating objects looks ok, accessing their attributes (numbers.. enums) as well. BUT, the problem is when i want to access a property which is actually a pointer... For instance, with this script: >>> from gerbv import * >>> >>> >>> >>> i = gerbv_instruction_t() >>> i <gerbv.gerbv_instruction_t object at 0x7f655abe6788> >>> i.opcode gerbv.gerbv_opcodes_t.GERBV_OPCODE_NOP >>> a = gerbv_amacro_t() >>> a <gerbv.gerbv_amacro_t object at 0x7f655abe67e0> >>> a.program Traceback (most recent call last): File "<stdin>", line 1, in <module> Boost.Python.ArgumentError: Python argument types in None.None(gerbv_amacro_t) did not match C++ signature: None(amacro {lvalue}) >>> I can't figure out what is happening here ! (you ll see that i am creating a proxy to access string and char array...) Any help is welcome :D Thanks a lot, Vivien Henry here the specific code for this error, which is in the file wrapper.cpp class gerbv_amacro_t_proxy: public gerbv_amacro_t{ public: std::string get_name(){ std::string s(name); return s; } void set_name(std::string s){ name = (gchar*)s.c_str(); } gerbv_amacro_t_proxy() { } }; // in boost_python macro... l655 class_<gerbv_amacro_t_proxy, boost::shared_ptr<gerbv_amacro_t_proxy> >("gerbv_amacro_t") //Methods //Properties .add_property("name", &gerbv_amacro_t_proxy::get_name, &gerbv_amacro_t_proxy::set_name) .add_property("program", make_getter(&gerbv_amacro_t_proxy::program, return_internal_reference<>()), make_setter(&gerbv_amacro_t_proxy::program, return_internal_reference<>())) .def_readwrite("nuf_push", &gerbv_amacro_t_proxy::nuf_push) .add_property("next", make_getter(&gerbv_amacro_t_proxy::next, return_internal_reference<>()), make_setter(&gerbv_amacro_t_proxy::next, return_internal_reference<>())) ; // in boost python macro l918 class_<gerbv_instruction_t, boost::shared_ptr<gerbv_instruction_t> >("gerbv_instruction_t") //Methods //Properties .def_readwrite("opcode", &gerbv_instruction_t::opcode) .def_readwrite("data", &gerbv_instruction_t::data) .add_property("next", make_getter(&gerbv_instruction_t::next, return_internal_reference<>()), make_setter(&gerbv_instruction_t::next, return_internal_reference<>())) ;

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