Mailman 3 March 2011 - Cplusplus-sig

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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CMake and getting starting with boost.python
by Braddock Gaskill Aug. 5, 2011

Aug. 5, 2011

Yesterday I became a boost.python user, after years of heavy SWIG usage. I would have started using boost.python years ago except for the bjam learning curve. I spent hours TRYING on multiple occasions, but got lost every time trying to get the page one example to build with bjam. Here is how to build the "greet" example with a four line CMake file: cat >>CMakeLists.txt <<EOF LINK_LIBRARIES(boost_python) INCLUDE_DIRECTORIES("/usr/include/python2.5") LINK_DIRECTORIES("/usr/lib/python2.5") # Not needed? ADD_LIBRARY(hello SHARED hello.cpp) EOF You WILL have to `mv libhello.so hello.so` after building. Works for me under Ubuntu Linux 6.10 after apt-get install cmake python2.5-dev boost-python-dev cmake make mv libhello.so hello.so ipython In [1]: import hello In [2]: hello.greet() Out[2]: 'hello, world' Boost.Python has been a joy to learn and use since I got past bjam. I had a moderately large API wrapped in just my first couple hours of learning (less time than I spent messing with bjam). Any additional advice for using CMake to build boost.python? Braddock Gaskill

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How to import a boost::python dll in windows?
by ichijoji Aug. 5, 2011

Aug. 5, 2011

I'm trying to port some research code that uses boost::python to expose a library to python to windows, but I'm having trouble importing the dll into python. I'm compiling using msvc 2005 and using python 2.5, but when I try to import the module I get this: Traceback (most recent call last): File "main.py", line 1, in <module> import object File "c:\code\sge\code\scripts\object.py", line 1, in <module> import sge ImportError: No module named sge My module is named sge and I'm compiling to sge.dll. Is there some obvious reason why python wouldn't be able to find my dll? When I compile on linux into an so this code works fine. -- View this message in context: http://www.nabble.com/How-to-import-a-boost%3A%3Apython-dll-in-windows--tf3… Sent from the Python - c++-sig mailing list archive at Nabble.com.

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Miscellaneous Boost.Python Utilities
by Jim Bosch July 6, 2011

July 6, 2011

In the hope that others might find them useful, and perhaps contribute some of their own, I've posted a collection of miscellaneous Boost.Python extensions I've been using at the Boost sandbox: http://svn.boost.org/svn/boost/sandbox/python_extensions Features include: - Conversions between STL containers and Boost.Range iterator ranges and Python builtins like list, tuple, and dict. - Conversions between Boost.Fusion sequences and Python tuples. - A third solution to the const shared_ptr problem (see http://language-binding.net/pyplusplus/troubleshooting_guide/shared_ptr/sha…) that isn't evil (I don't think) and doesn't involve changing the Boost.Python library itself - it simply doesn't use register_ptr_to_python to register the conversion. More info is available in the README file. Also, I'm sure many of the regulars on this list have their own similar extensions, and I'd love to see them collected in one place. If you'd like to add your collection to mine, or have a suggestion for some other place I should put my collection, please let me know. I would like to limit this collection to simple things that don't depend on non-Boost libraries, however. Jim Bosch

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GSoC Boost.Python project
by Ankit Daftery March 31, 2011

March 31, 2011

Hello I am working on the project proposal for GSoC 2011 for the Boost.python project, and I would like a little help. 1. ndarray.hpp mentions that functionality needs to be added like the one in boost::python::numeric::array . Stefan suggested that Jim might be able to help with what exactly was intended. Is there anything specific in mind ? 2. Neal mentions that efficiency needs to be improved. Could you please help me with a little more detail about that, Neal ? 3. ndarray.hpp also mentions that the templates "Should probably take ranges of iterators rather than actual container objects." Could someone explain what is intended ? Am I missing out on something essential ? Anything I should keep in mind ? Tips and pointers. Please help me out here. Thanks, Ankit

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segfault wrapping iterator_facade input iterators
by Alec Chapman March 30, 2011

March 30, 2011

Hi all, I'm having some trouble using boost.python to expose an input iterator that I've implemented using boost::iterator_facade. I've included an example below. The code will print garbage when iterating in python and segfault for more complicated iterators, but works fine if std::input_iterator_tag is changed to forward_iterator_tag. I've noticed this happens in VC9 and gcc. The problem goes away if line 65 in boost/python/object/iterator.hpp is changed from "return *self.m_start++;" to something like: result_type r = *self.m_start; ++self.m_start; return r; It seems that this change should be made for input iterators, since the postfix increment operator is allowed to return void. However, I don't fully understand why this is a problem in my case since iterator_facade returns a proxy iterator that can be dereferenced. Thanks for any help, Alec #include <boost/python.hpp> #include <boost/iterator/iterator_facade.hpp> using namespace boost::python; class container { public: class iter : public boost::iterator_facade<iter, int, std::input_iterator_tag> { public: iter(int* i) : m_i(i) {} private: friend class boost::iterator_core_access; void increment() { m_i++; } int& dereference() const { return *m_i; } bool equal(const iter& other) const { return m_i == other.m_i; } int* m_i; }; container() : m_data() {} iter begin() { return iter(m_data); } iter end() { return iter(m_data+5); } private: int m_data[5]; }; BOOST_PYTHON_MODULE(iter_example) { class_<container>("container") .add_property("data", range(&container::begin, &container::end)) ; } ------------------------------------------ import iter_example c = iter_example.container() for x in c.data: print x

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GSoC 2011 proposal for improved NumPy wrapper ?
by Stefan Seefeld March 25, 2011

March 25, 2011

Hello, As you may have heard, Boost has once again been accepted as a mentoring organization in this year's Google Summer of Code program. One of the potential projects that we have been talking about in the past is about improving the NumPy wrapper in Boost.Python. We talked about different shortcomings with the existing "numeric" module, and why a richer API to access NumPy would be useful. Some code to address these shortcomings already exists, and may be used as a starting point for such Boost.Python improvements. Anyone considering to work on this, please get in touch ! Stefan -- ...ich hab' noch einen Koffer in Berlin...

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language-binding.net website not available
by Maciej Sitarz March 25, 2011

March 25, 2011

Hi since some time the Py++ project's homepage is down. Does anyone know why? Was it moved somewhere or there's some mirror available? I also haven't seen Roman Yakovenko posting here recently. Thanks for any info. Regards -- Maciek Sitarz

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boost::python::set missing?
by Wichert Akkerman March 21, 2011

March 21, 2011

I noticed that the standard python set type is not exposed. Are there any plans to add that? Wichert. -- Wichert Akkerman <wichert(a)wiggy.net> It is simple to make things. http://www.wiggy.net/ It is hard to make things simple.

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problem importing PyEphem when using Python in debug mode.
by Rich A March 15, 2011

March 15, 2011

Okay, I'm stumped, and I'm hoping someone here can help me. I'm writing a C++ wrapper for PyEphem so I've built a debug version of Python for development. When I import PyEphem in the release Python version, no problem. But using the debug version I get the error: No module named _libastro. Here's what I'm seeing: c:\python27> c:\python27>python Python 2.7.1 (r271:86832, Nov 27 2010, 18:30:46) [MSC v.1500 32 bit (Intel)] on Type "help", "copyright", "credits" or "license" for more information. >>> import ephem >>> c:\python27>python_d Python 2.7.1 (r271:86832, Mar 9 2011, 08:13:52) [MSC v.1500 32 bit (Intel)] on Type "help", "copyright", "credits" or "license" for more information. >>> import ephem Traceback (most recent call last): File "<stdin>", line 1, in <module> File "c:\python27\lib\site-packages\ephem\__init__.py", line 5, in <module> import ephem._libastro as _libastro ImportError: No module named _libastro [43417 refs] >>> __init__.py, line 5 indeed, does import ephem._libastro as _libastro, but why does it work for the release version and not the debug version? Nothings moved, all I did was add python_d.exe and python27_d.dll to the c:\python27 directory. There must be some mechanism for locating modules that hasn't/isn't being configured with the debug executable. I know this has got to be simple but it's driving me to distraction. Thanks in advance for any help.

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