Mailman 3 July 2012 - 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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sendkeys method
by sam Sept. 30, 2013

Sept. 30, 2013

Hello, Is there away(method) in C/C++ programming that make the software think that someone pressed the OK button, similar to sendkeys in VBS (WshShell.SendKeys ("{Enter}")) Thank you, Sam

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How to create a custom exception derived from Exception
by Glenn Ramsey Aug. 2, 2012

Aug. 2, 2012

Using boost::python how can I create an a custom exception that is derived from Python's Exception? The functionality I would like to get by doing this is to provide additional methods for the catching code to retrieve information from the exception. I know it is possible to just wrap and throw my own exception class but it seems that because it is not derived from Exception then in certain situations I get the error "SystemError: 'finally' pops bad exception". This example [1] shows how to wrap a C++ exception class... class MyCPPException : public std::exception {...} using namespace boost::python; ... PyObject *myCPPExceptionType=0; void translate(MyCPPException const &e) { PyErr_SetObject(myCPPExceptionType, object(e).ptr()); } BOOST_PYTHON_MODULE(MyModule) { ... class_<MyCPPException> myCPPExceptionClass("MyCPPException"...); myCPPExceptionClass .def("get_extra_info", &MyCPPException::get_extra_info); myCPPExceptionType=myCPPExceptionClass.ptr(); register_exception_translator<MyCPPException>(&translate); ... } But this is not derived from Exception. This example [2] shows how to create an exception that is derived from Exception. PyObject* createExceptionClass(const char* name, PyObject* baseTypeObj = PyExc_Exception) { using std::string; namespace bp = boost::python; string scopeName = bp::extract<string>(bp::scope().attr("__name__")); string qualifiedName0 = scopeName + "." + name; char* qualifiedName1 = const_cast<char*>(qualifiedName0.c_str()); PyObject* typeObj = PyErr_NewException(qualifiedName1, baseTypeObj, 0); if(!typeObj) bp::throw_error_already_set(); bp::scope().attr(name) = bp::handle<>(bp::borrowed(typeObj)); return typeObj; } PyObject* myExceptionTypeObj = 0; void translate(MyCPPException const &e) { PyErr_SetObject(myExceptionTypeObj, object(e).ptr()); } BOOST_PYTHON_MODULE(MyModule) { register_exception_translator<MyCPPException>(&translateFunc); ... myExceptionTypeObj = createExceptionClass("MyException"); ... } But this doesn't have any custom methods to get info from the exception. How can I do both at the same time? Glenn [2] <http://stackoverflow.com/questions/9620268/boost-python-custom-exception-cl…> [1] <http://stackoverflow.com/questions/2261858/boostpython-export-custom-except…>

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Indexing suite v2 multiple module problem
by John Reid July 25, 2012

July 25, 2012

Hi, I'm using a version of the indexing suite I believe I copied from Roman's codebase some time ago. I've recently refactored my project into multiple modules and now I'm have some runtime errors when iterating over sequences in python. At runtime I get the cryptic message: RuntimeError: get It is proving a little difficult to track down as it only happens on my server not on my development machine although it is reproducible every time. Not all std::vectors that are exposed trigger the error. If I change the order that my C++ modules are imported then the std::vector that triggers the error changes. I'm building a debug python on my server to try to investigate further but meanwhile I wonder if anyone had any suggestions or had seen this sort of thing before? Also where is the latest version of the indexing suite v2 code that I could use? Thanks, John.

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Boost Python support Python Version.
by Harkirat Singh July 23, 2012

July 23, 2012

Hi all I will be extending custom libraries to python. My target system uses python2.4.4. I have even tried swig, but it seems there isnt full support for python2.4. It uses some python c++ API not supported in python2.4.4. What is the status of boost python regarding this. Thanks Sam

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Factory using embedded Python interpreter
by Wojciech Mamrak July 21, 2012

July 21, 2012

Hello list, I am trying to create C++ objects dynamically (some kind of factory) with use of embedded Python interpreter (i.e. eval). Naive implementation: namespace bp = boost::python; bp::object main_module = ...; bp::object main_namespace = ...; bp::object bpo_ob = bp::eval((type+"()").c_str(), main_namespace); Object* ob = bp::extract<Object*>(pbo_ob); Simple eval returns bp::object, so after it goes out of scope PyDECREF is called and finally Python's garbage collector wipes Object out. Based on FAQ's entry: http://www.boost.org/doc/libs/1_50_0/libs/python/doc/v2/faq.html#ownership I set held_type to std::auto_ptr in Object definition: BOOST_PYTHON_MODULE(MyModule) { class_<Object, std::auto_ptr<Object>>("Object", init<>()); } but I am not sure how to take the ownership over objects created this way. I was thinking about: bp::object bpo_ob = bp::eval((type+"()").c_str(), main_namespace); std::auto_ptr<Object> ob = bp::extract<std::auto_ptr<Object>>(bpo_ob); Object* o = ob.release(); but I am not sure about its correctness with respect to memory leaks. When run, the program does not crash. Thanks!

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exporting a boost::python::dict containing a boost::python::list
by Ronny Herzog July 21, 2012

July 21, 2012

Dear all, I want to export a boost::python::dict containing a boost::python::list. However, when I print this list in Python, I get an unlimited output of some strange numbers: namespace bp = boost::python; class readraw { .... bp::list mk_pyPeak_list() { bp::list py_peak_list; for (int i = 0; i < peak_number; i++) { py_peak_list.append(bp::make_tuple(peak_list[0][i].mz, peak_list[0][i].intensity)); } return py_peak_list; } bp::dict peak_list_info() { bp::dict info; //bp::object pn = peak_number; //info["peakNumber"] = peak_number; //std::cout << bp::extract<int>(mk_pyPeak_list().attr("__len__")(); bp::list l(mk_pyPeak_list()); info["peakList"] = l; return info; } }; BOOST_PYTHON_MODULE(readraw) { bp::class_<readraw>("readraw", bp::init<int>()) .def("add_peak", &readraw::add_peak) .def("peak_list_info", &readraw::peak_list_info) .def("average_scans", &readraw::average_scans) ; In Python: >>> print rawfilereader.peak_list_info() Results in smth. like: ... (-431602080.0, -6.2774385622041925e+66), (-431602080.0, -6.2774385622041925e+66 ), (-431602080.0, -6.2774385622041925e+66), (-431602080.0, -6.2774385622041925e+ 66), (-431602080.0, -6.2774385622041925e+66), (-431602080.0, -6.2774385622041925 e+66), (-431602080.0, -6.2774385622041925e+66), (-431602080.0, -6.27743856220419 25e+66), (-431602080.0, -6.2774385622041925e+66), (-431602080.0, -6.277438562204 1925e+66), (-431602080.0, -6.2774385622041925e+66), (-431602080.0, -6.2774385622 041925e+66), (-431602080.0, -6.2774385622041925e+66), (-431602080.0, -6.27743856 ... What am I doing wrong? Thanks for the help, Ronny

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unable to build boost.python with gcc 3.3.5 and python2.4 : compilation error
by Harkirat Singh July 19, 2012

July 19, 2012

While compiling boost.python particularly, i get this error. Is there any workaround on this. * In file included from boost/unordered/detail/emplace_args.hpp:16, from boost/unordered/detail/allocator_helpers.hpp:18, from boost/unordered/unordered_set.hpp:17, from boost/unordered_set.hpp:16, from boost/graph/adjacency_list.hpp:21, from libs/python/src/object/inheritance.cpp:11: boost/move/move.hpp:124: warning: all member functions in class ` boost::move_detail::is_convertible<T, U>' are private boost/move/move.hpp:254: warning: `class boost::rv<T>' only defines a private destructor and has no friends In file included from boost/range/size.hpp:21, from boost/range/functions.hpp:20, from boost/range/iterator_range_core.hpp:26, from boost/range/iterator_range.hpp:13, from boost/range/irange.hpp:16, from boost/graph/detail/adjacency_list.hpp:20, from boost/graph/adjacency_list.hpp:337, from libs/python/src/object/inheritance.cpp:11: boost/range/size_type.hpp:41: warning: all member functions in class ` boost::detail::has_size_type<T>' are private libs/python/src/object/inheritance.cpp:114: sorry, unimplemented: use of ` enumeral_type' in template type unification * Regards Harkirat Singh

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boost python/example/quickstart does not work
by Ronny Herzog July 18, 2012

July 18, 2012

Dear all, I am experiencing a problem with the quickstart example from boost for Python. This is what happens: >>> c:\boost_1_50_0\libs\python\example\quickstart>bjam --toolset=msvc --verbose-test test ...patience... ...patience... ...found 1652 targets... ...updating 4 targets... msvc.link bin\test_embed.test\msvc-9.0\debug\threading-multi\test_embed.exe LINK : warning LNK4001: no object files specified; libraries used LINK : error LNK2001: unresolved external symbol _mainCRTStartup bin\test_embed.test\msvc-9.0\debug\threading-multi\test_embed.exe : fatal error LNK1120: 1 unresolved externals call "C:\Program Files\Microsoft Visual Studio 9.0\VC\vcvarsall.bat" x86 >nul link /NOLOGO /INCREMENTAL:NO /DEBUG /MACHINE:X86 /subsystem:console /out:"bin\te st_embed.test\msvc-9.0\debug\threading-multi\test_embed.exe" /LIBPATH:"c:\Python 26\libs" @"bin\test_embed.test\msvc-9.0\debug\threading-multi\test_embed.exe.rs p" if %ERRORLEVEL% NEQ 0 EXIT %ERRORLEVEL% ...failed msvc.link bin\test_embed.test\msvc-9.0\debug\threading-multi\test_embe d.exe bin\test_embed.test\msvc-9.0\debug\threading-multi\test_embed.pdb... ...removing bin\test_embed.test\msvc-9.0\debug\threading-multi\test_embed.pdb ...skipped <pbin\test_embed.test\msvc-9.0\debug\threading-multi>test_embed.run f or lack of <pbin\test_embed.test\msvc-9.0\debug\threading-multi>test_embed.exe.. . ...failed updating 2 targets... ...skipped 2 targets... <<< It somehow does not find the vcvarsall.bat although it is right in the place. I even started it before I run bjam. Any help is appriciated. Ronny

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Instance ownership transfer in constructor.
by Jani Tiainen July 6, 2012

July 6, 2012

Hi, I'm new to python.boost library and I'm trying to use it to wrap a third party library. Everything else I've managed to get working - thanks to excellent library and lot of examples I've found around a net. Only thing I can't get working properly is instance ownership transfer in constructor. So classes in library are defined like follows: class Owner { ... } class Data { Data(Owner *owner); // <-- Here happens ownership transfer. } Python code is like follows: owner = Owner() data_1 = Data(owner) data_2 = Data(owner) So when Python script stops runnning it causes crash due the fact that I've data objects are automatically destroyed by Owner-class but Python deletes them by using Data-class destructor (which shouldn't happen ever). -- Jani Tiainen - Well planned is half done and a half done has been sufficient before...

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