Mailman 3 March 2009 - 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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Getting object for PyObject (reference counting)
by Murray Cumming Feb. 11, 2010

Feb. 11, 2010

I can't find any definitive documentation that tells me how I should get a boost::python::object to wrap an existing PyObject*. I guess that there's a way to do it that uses an existing reference, and a way that takes an extra reference. -- murrayc(a)murrayc.com www.murrayc.com www.openismus.com

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strange behavior with respect to numeric and Boolean overloads
by Matthew Scouten (TT) April 13, 2009

April 13, 2009

So here is some strange behavior I ran across with BP. A take a look at this example code: busybox.cpp: #include "stdafx.h" std::string foo_int (int arg) { return std::string("foo(int) Called"); } std::string foo_double(double arg) { return std::string("foo(double) Called"); } std::string foo_bool (bool arg) { return std::string("foo(bool) Called"); } BOOST_PYTHON_MODULE(busybox) { bp::def("foo", foo_double); bp::def("foo", foo_bool); bp::def("foo", foo_int); } python Interpreter: Python 2.6.1 (r261:67517, Dec 4 2008, 16:51:00) [MSC v.1500 32 bit (Intel)] on win32 Type "help", "copyright", "credits" or "license" for more information. >>> import busybox >>> busybox.foo(5.0) 'foo(double) Called' >>> busybox.foo(5) 'foo(int) Called' >>> busybox.foo(True) 'foo(int) Called' >>> Note that the int overload is called for a bool argument. If I change the order of the defs in the cpp file I can effect this to some extent. If I put the def for the bool overload last, IT gets called for both int and bool parameters. If I put the double override last, that override gets called for ALL 3 CALLS regardless of what is passed. Now the order sensitivity is annoying, but I can figure out how to make it work right, and then comment the dickens out of the code. The real killer is that there does not seem to be any way to force BP to differentiate between a bool and an int. The only thing that has worked is to apply a name skew (ie: bp::def("foo_bool", foo_bool);). This works, but the users carp at me for changing the interface from the underlying library. Is there a better work around? Is this a bug?

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Some thoughts on py3k support
by Haoyu Bai April 9, 2009

April 9, 2009

Hi, Here is some thoughts on GSoC Boost.Python py3k support project. First thing come into my mind is the build system. For Python 3, we would have a separate build target, eg. having libboost_python.so built for Python 2.x and libboost_python3.so for Python 3. This would match the current situation that most Linux distro packaged Python 3 in a way that lives together with Python 2.x. There's two build system for Boost now - cmake and bjam. Personally I want to start with cmake, and finally both of the two will up to date for Python 3. I have read some piece of Boost.Python code in these, it is understandable for me. And I'd say the usage of template metaprogramming is really smart! Thanks to the high level abstraction, there would be just a little code interfaced to Python C-API directly. So there would not be so much works. However there are something we need to take care of. One of them is, in Python 3, string is unicode (and the old string class is called bytes in Python 3). So if we have a C function char const* hello(); // returns a "Hello" According to the current behavior of Boost.Python converters, the wrapped function in Python 3 will return a b"Hello" (which is a bytes object but not a string). So code like this will broken: if "Hello" == hello(): ... Because string object "Hello" is not equal to bytes object b"Hello" returned by hello(). We may change the behavior of converter to return a unicode string in Python 3, that would keep most of existing code compatible. Anyway there will be code really need a single byte string returned, a new converter can be explicitly specified for this. There are more issues similar to this. I'll figure out more and write a detailed proposal as soon as possible. Best regards, Haoyu Bai

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instantiate python classes in c++
by Gregor Burger April 4, 2009

April 4, 2009

hi all, is it possible to use boost.python to define classes in a script (like in the one below), register the defined classes and later on create instances of the class? from cd3 import * class MyNode(Node): def init(self, start, stop, dt): in_flow = Flow() self.addInPort(in_flow) def f(self, time, dt): return dt register_node(MyNode) registering of the class is working also instantiating the class. but it seems that when i call init(...) and f(...) afterwards the namespace and all imports are lost. so in_flow = Flow() raises an global name Flow undefined. The wrapping of Flow works on first execution. Is it possible to provide the same globals and locals to call_method so that Flow and other classes are defined? thanks in advance. gregor burger university of innsbruck the wrapped Node looks like this: struct NodeCallback : Node { NodeCallback(PyObject *p) : self(p) { Py_INCREF(self); } virtual ~NodeCallback() { Py_DECREF(self); } void init(int start, int stop, int dt) { call_method<void, int, int, int>(self, "init", start, stop, dt); } int f(int time, int dt) { return call_method<int, int, int>(self, "f", time, dt); } void addInPort(object o) { std::string name = extract<std::string>(o.attr("__name__")); std::cout << "adding in port " << name << std::endl; } PyObject *self; };

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map_indexing_suite interface
by troy d. straszheim April 1, 2009

April 1, 2009

I'm wondering why the current map_indexing_suite is the way it is. Is there any reason not to enhance it to support now standard methods like keys(), values(), popitem() and the like? -t

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[Py++] compilation errors
by Michał Nowotka March 29, 2009

March 29, 2009

Hello, when generating binding code using Py++ i got following warnings: WARNING: hapl::Fenotype const * hapl::Fenotypes::find_equal(hapl::Fenotype const & pattern) const [member function] > compilation error W1050: The function returns "hapl::Fenotype const *" type. You have to specify a call policies.Be sure to take a look on Py++ defined > call policies: http://language-binding.net/pyplusplus/documentation/functions/call_policie… WARNING: hapl::Fenotype * hapl::Fenotypes::find_equal(hapl::Fenotype const & pattern) [member function] > compilation error W1050: The function returns "hapl::Fenotype *" type. You have to specify a call policies.Be sure to take a look on Py++ defined call > policies: http://language-binding.net/pyplusplus/documentation/functions/call_policie… WARNING: hapl::Haplotype const * hapl::Haplotypes::find_equal(hapl::Haplotype const & pattern) const [member function] > compilation error W1050: The function returns "hapl::Haplotype const *" type. You have to specify a call policies.Be sure to take a look on Py++ defined > call policies: http://language-binding.net/pyplusplus/documentation/functions/call_policie… WARNING: hapl::Haplotype const * hapl::Genotype::getUp() const [member function] > compilation error W1050: The function returns "hapl::Haplotype const *" type. You have to specify a call policies.Be sure to take a look on Py++ defined > call policies: http://language-binding.net/pyplusplus/documentation/functions/call_policie… WARNING: hapl::Haplotype const * hapl::Genotype::getDown() const [member function] > compilation error W1050: The function returns "hapl::Haplotype const *" type. You have to specify a call policies.Be sure to take a look on Py++ defined > call policies: http://language-binding.net/pyplusplus/documentation/functions/call_policie… WARNING: hapl::Fenotype const * hapl::Genotype::getFenotype() const [member function] > compilation error W1050: The function returns "hapl::Fenotype const *" type. You have to specify a call policies.Be sure to take a look on Py++ defined > call policies: http://language-binding.net/pyplusplus/documentation/functions/call_policie… so I found all function declarations returning 'hapl::Fenotype const *' and ' hapl::Haplotype const *' in my header files and assigned call policies: mb.member_function( 'getLocus' ).call_policies = module_builder.call_policies.return_internal_reference() mb.member_functions( 'findVariant' ).call_policies = module_builder.call_policies.return_internal_reference() mb.member_functions( 'find_equal' ).call_policies = module_builder.call_policies.return_internal_reference() mb.member_function( 'getUp' ).call_policies = module_builder.call_policies.return_internal_reference() mb.member_function( 'getDown' ).call_policies = module_builder.call_policies.return_internal_reference() mb.member_function( 'getFenotype' ).call_policies = module_builder.call_policies.return_internal_reference() now all warnings disappeared. But when compiling output file i got some errors: /usr/include/boost/python/detail/invoke.hpp: In function 'PyObject* boost::python::detail::invoke(boost::python::detail::invoke_tag_<false, false>, const RC&, F&, AC0&) [with RC = boost::python::detail::caller_arity<1u>::impl<F, Policies, Sig>::operator()(PyObject*, PyObject*) [with F = const hapl::Fenotype* (*)(std::pair<const hapl::Fenotype* const, double>&), Policies = boost::python::default_call_policies, Sig = boost::mpl::vector2<const hapl::Fenotype*, std::pair<const hapl::Fenotype* const, double>&>]::result_converter, F = const hapl::Fenotype* (*)(std::pair<const hapl::Fenotype* const, double>&), AC0 = boost::python::detail::caller_arity<1u>::impl<F, Policies, Sig>::operator()(PyObject*, PyObject*) [with F = const hapl::Fenotype* (*)(std::pair<const hapl::Fenotype* const, double>&), Policies = boost::python::default_call_policies, Sig = boost::mpl::vector2<const hapl::Fenotype*, std::pair<const hapl::Fenotype* const, double>&>]::c_t0]': /usr/include/boost/python/detail/caller.hpp:199: instantiated from 'PyObject* boost::python::detail::caller_arity<1u>::impl<F, Policies, Sig>::operator()(PyObject*, PyObject*) [with F = const hapl::Fenotype* (*)(std::pair<const hapl::Fenotype* const, double>&), Policies = boost::python::default_call_policies, Sig = boost::mpl::vector2<const hapl::Fenotype*, std::pair<const hapl::Fenotype* const, double>&>]' /usr/include/boost/python/object/py_function.hpp:38: instantiated from 'PyObject* boost::python::objects::caller_py_function_impl<Caller>::operator()(PyObject*, PyObject*) [with Caller = boost::python::detail::caller<const hapl::Fenotype* (*)(std::pair<const hapl::Fenotype* const, double>&), boost::python::default_call_policies, boost::mpl::vector2<const hapl::Fenotype*, std::pair<const hapl::Fenotype* const, double>&> >]' bindings.cpp:780: instantiated from here /usr/include/boost/python/detail/invoke.hpp:75: error: no match for call to '(const boost::python::detail::specify_a_return_value_policy_to_wrap_functions_returning<const hapl::Fenotype*>) (const hapl::Fenotype*)' /usr/include/boost/python/detail/invoke.hpp: In function 'PyObject* boost::python::detail::invoke(boost::python::detail::invoke_tag_<false, false>, const RC&, F&, AC0&) [with RC = boost::python::detail::caller_arity<1u>::impl<F, Policies, Sig>::operator()(PyObject*, PyObject*) [with F = const hapl::Genotype* (*)(std::pair<const hapl::Genotype* const, double>&), Policies = boost::python::default_call_policies, Sig = boost::mpl::vector2<const hapl::Genotype*, std::pair<const hapl::Genotype* const, double>&>]::result_converter, F = const hapl::Genotype* (*)(std::pair<const hapl::Genotype* const, double>&), AC0 = boost::python::detail::caller_arity<1u>::impl<F, Policies, Sig>::operator()(PyObject*, PyObject*) [with F = const hapl::Genotype* (*)(std::pair<const hapl::Genotype* const, double>&), Policies = boost::python::default_call_policies, Sig = boost::mpl::vector2<const hapl::Genotype*, std::pair<const hapl::Genotype* const, double>&>]::c_t0]': /usr/include/boost/python/detail/caller.hpp:199: instantiated from 'PyObject* boost::python::detail::caller_arity<1u>::impl<F, Policies, Sig>::operator()(PyObject*, PyObject*) [with F = const hapl::Genotype* (*)(std::pair<const hapl::Genotype* const, double>&), Policies = boost::python::default_call_policies, Sig = boost::mpl::vector2<const hapl::Genotype*, std::pair<const hapl::Genotype* const, double>&>]' /usr/include/boost/python/object/py_function.hpp:38: instantiated from 'PyObject* boost::python::objects::caller_py_function_impl<Caller>::operator()(PyObject*, PyObject*) [with Caller = boost::python::detail::caller<const hapl::Genotype* (*)(std::pair<const hapl::Genotype* const, double>&), boost::python::default_call_policies, boost::mpl::vector2<const hapl::Genotype*, std::pair<const hapl::Genotype* const, double>&> >]' bindings.cpp:780: instantiated from here /usr/include/boost/python/detail/invoke.hpp:75: error: no match for call to '(const boost::python::detail::specify_a_return_value_policy_to_wrap_functions_returning<const hapl::Genotype*>) (const hapl::Genotype*)' /usr/include/boost/python/detail/invoke.hpp: In function 'PyObject* boost::python::detail::invoke(boost::python::detail::invoke_tag_<false, false>, const RC&, F&, AC0&) [with RC = boost::python::detail::caller_arity<1u>::impl<F, Policies, Sig>::operator()(PyObject*, PyObject*) [with F = const hapl::Haplotype* (*)(std::pair<const hapl::Haplotype* const, double>&), Policies = boost::python::default_call_policies, Sig = boost::mpl::vector2<const hapl::Haplotype*, std::pair<const hapl::Haplotype* const, double>&>]::result_converter, F = const hapl::Haplotype* (*)(std::pair<const hapl::Haplotype* const, double>&), AC0 = boost::python::detail::caller_arity<1u>::impl<F, Policies, Sig>::operator()(PyObject*, PyObject*) [with F = const hapl::Haplotype* (*)(std::pair<const hapl::Haplotype* const, double>&), Policies = boost::python::default_call_policies, Sig = boost::mpl::vector2<const hapl::Haplotype*, std::pair<const hapl::Haplotype* const, double>&>]::c_t0]': /usr/include/boost/python/detail/caller.hpp:199: instantiated from 'PyObject* boost::python::detail::caller_arity<1u>::impl<F, Policies, Sig>::operator()(PyObject*, PyObject*) [with F = const hapl::Haplotype* (*)(std::pair<const hapl::Haplotype* const, double>&), Policies = boost::python::default_call_policies, Sig = boost::mpl::vector2<const hapl::Haplotype*, std::pair<const hapl::Haplotype* const, double>&>]' /usr/include/boost/python/object/py_function.hpp:38: instantiated from 'PyObject* boost::python::objects::caller_py_function_impl<Caller>::operator()(PyObject*, PyObject*) [with Caller = boost::python::detail::caller<const hapl::Haplotype* (*)(std::pair<const hapl::Haplotype* const, double>&), boost::python::default_call_policies, boost::mpl::vector2<const hapl::Haplotype*, std::pair<const hapl::Haplotype* const, double>&> >]' bindings.cpp:780: instantiated from here /usr/include/boost/python/detail/invoke.hpp:75: error: no match for call to '(const boost::python::detail::specify_a_return_value_policy_to_wrap_functions_returning<const hapl::Haplotype*>) (const hapl::Haplotype*)' this is strange for me bacause I'm sure I listed all methods returning mentioned types. There is also one more type that doesn't cause warning: '(const hapl::Genotype*' So I guess this problem may be caused by typedef declaration in my header files: typedef std::map<const Haplotype*,double> ProbHaplotype; typedef std::map<const Fenotype*,double> ProbFenotype; typedef std::map<const Genotype*,double> ProbGenotype; and: typedef std::set<const Fenotype*> ObsFenotypes; typedef std::set<const Genotype*> ObsGenotypes; typedef std::set<const Haplotype*> ObsHaplotypes; STL generic containers can generate methods returning problematic types so i cannot see it in my headers. To solve this problem I replaced lines with call polices mentioned above by: mb.member_functions(return_type='hapl::Fenotype const *').call_policies = module_builder.call_policies.return_internal_reference() mb.member_functions(return_type='hapl::Haplotype const *').call_policies = module_builder.call_policies.return_internal_reference() mb.member_functions(return_type='hapl::Genotype const *').call_policies = module_builder.call_policies.return_internal_reference() but this causes run time error: Traceback (most recent call last): File "makewindow.py", line 27, in <module> mb.member_functions(return_type='hapl::Fenotype const *').call_policies = module_builder.call_policies.return_internal_reference() File "/usr/lib/python2.5/site-packages/pyplusplus/module_builder/builder.py", line 564, in member_functions , recursive=recursive) File "/usr/lib/python2.5/site-packages/pygccxml/declarations/scopedef.py", line 518, in member_functions , allow_empty=allow_empty) File "/usr/lib/python2.5/site-packages/pygccxml/declarations/scopedef.py", line 374, in _find_multiple raise RuntimeError( "Multi declaration query returned 0 declarations." ) RuntimeError: Multi declaration query returned 0 declarations. So what shuld I do to get clean complation without errors? -- Regards Michał Nowotka

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[Py++] free operators
by Michał Nowotka March 29, 2009

March 29, 2009

Hello, I want to expose to python following code: typedef std::map<const Haplotype*,double> ProbHaplotype; typedef std::map<const Fenotype*,double> ProbFenotype; typedef std::map<const Genotype*,double> ProbGenotype; (...) std::ostream& operator<<(std::ostream& os, const ProbHaplotype& hapl); std::ostream& operator<<(std::ostream& os, const ProbFenotype& fen); std::ostream& operator<<(std::ostream& os, const ProbGenotype& gen); but I get some warnings: WARNING: extern std::ostream & hapl::operator<<(std::ostream & os, hapl::ProbGenotype const & gen) [free operator] > warning W1052: Py++ will not expose free operator "extern std::ostream & hapl::operator<<(std::ostream & os, hapl::ProbGenotype const & gen) [free > operator]" - all classes, this operator works on, are excluded. WARNING: extern std::ostream & hapl::operator<<(std::ostream & os, hapl::ProbFenotype const & fen) [free operator] > warning W1052: Py++ will not expose free operator "extern std::ostream & hapl::operator<<(std::ostream & os, hapl::ProbFenotype const & fen) [free > operator]" - all classes, this operator works on, are excluded. WARNING: extern std::ostream & hapl::operator<<(std::ostream & os, hapl::ProbHaplotype const & hapl) [free operator] > warning W1052: Py++ will not expose free operator "extern std::ostream & hapl::operator<<(std::ostream & os, hapl::ProbHaplotype const & hapl) [free > operator]" - all classes, this operator works on, are excluded. How can I get rid of it? -- Regards, Michał Nowotka

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