Mailman 3 November 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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outdated info in the "projects using boost.python" docs
by Greg Landrum Dec. 17, 2012

Dec. 17, 2012

Hi, A colleague pointed out to me that the "Project using Boost.Python" document (http://www.boost.org/doc/libs/1_52_0/libs/python/doc/projects.html) includes a link to Rational Discovery LLC, a company that no longer exists (we shut it down in 2006). That link, which now re-directs to some completely different organization) should probably be removed. The software we developed that uses boost.python to expose chemistry functionality in C++ to Python has been open-sourced as the rdkit (www.rdkit.org). If there's any interest in new additions to the "projects using boost.python" page, I would be happy to provide a blurb. Thanks, -greg

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free() of null-pointing handle<> throws SIGABRT
by Martin Hellmich Nov. 29, 2012

Nov. 29, 2012

Hi, in my exception handling (based on a tutorial, which I can dig up if it helps), I create handles for the exc, val, tb values of an exception thrown in python. The code is shown below in extractException(). It is a shortened version, which does not cover all possible cases. In some cases, val is defined, but tb is not. When then htb points to 0x0, the function fails with a SIGABRT as it returns. I believe that the free() for the htb fails, when it goes out of scope at the end of the function. I put the Error message and the GDB output at the end of the mail. The address at which the free() fails is likely the one of tb, as it sits inbetween exc and val in memory. Other calls to extractException() where tb is not null do not abort. Do you have an idea why the free() could fail? I am happy to post more information, if needed and would welcome any hints :) Cheers Martin void PythonExceptionHandler::extractException() throw (DmException) { using namespace boost::python; PyObject *exc,*val,*tb; PyErr_Fetch(&exc,&val,&tb); PyErr_NormalizeException(&exc,&val,&tb); handle<> hexc(exc),hval(allow_null(val)),htb(allow_null(tb)); int code = 0; std::string what = ""; if (PyObject_HasAttrString(val, "code") && PyObject_HasAttrString(val, "what")) { object oval(hval); extract<int> get_code(oval.attr("code")()); extract<std::string> get_what(oval.attr("what")()); code = get_code(); what = get_what(); throw DmException(code, what); } else { std::string excString; excString = extract<std::string>(str(hexc)); throw DmException(DMLITE_SYSERR(DMLITE_UNKNOWN_ERROR), excString); } } Error Message: *** glibc detected *** /usr/lib64/dmlite/test/cpp/test-replicas: free(): invalid pointer: 0x0000003a4c5a0d60 *** GDB output: (gdb) p htb $6 = {m_p = 0x0} (gdb) p tb $7 = (PyObject *) 0x0 (gdb) info locals val = 0x3a4c5a0d80 tb = 0x0 hexc = {m_p = 0x3a4c579ea0} what = "" exc = 0x3a4c579ea0 hval = {m_p = 0x3a4c5a0d80} htb = {m_p = 0x0} code = <value optimized out> -- Martin Hellmich Information Technology Department mhellmic(a)cern.ch CERN +41 22 76 765 26 CH-1211 Geneva 23

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Boost chooses wrong static library
by Wojciech Mamrak Nov. 29, 2012

Nov. 29, 2012

Hello, I have built Python's (2.7.3) debugging version under Windows, added "<python-debugging>on" in user-config.jam, then run bjam: bjam -j4 --toolset=msvc --with-python python-debugging=on variant=debug link=static runtime-link=static,shared in a.cpp file I included boost python headers this way: #define BOOST_PYTHON_STATIC_LIB #define BOOST_DEBUG_PYTHON #include <boost/python.hpp> Since BOOST_DEBUG_PYTHON is defined, I linked against libboost_python-vc100-mt-gyd-1_52.lib, but when compiling, the linker complains: LINK : fatal error LNK1104: cannot open file 'libboost_python-vc100-mt-gd-1_52.lib' What am I missing? Why does boost expect different static library file? regards

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please remove me from mailing list
by Chandler Gegg Nov. 19, 2012

Nov. 19, 2012

thank you

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a boost.python question about parameter that is a pointer of instance.
by simon zhang Nov. 17, 2012

Nov. 17, 2012

This is a complex problem. I provide some code. c++ ======================================= #include <boost/python.hpp> #include <boost/python/module.hpp> #include <boost/python/def.hpp> class Rectangle { public: Rectangle(); virtual ~Rectangle(); void set(int lg,int wd) { long=lg; width=wd; }; int area() { return long*width; } ; int long; int width; } void runtest( boost::python::object &func ) { Rectangle rt; rt.set(2,3); func( &rt ); // The parameter is a pointer of instance.The function come from python. } BOOST_PYTHON_MODULE(ctopython) { using namespace boost::python; def("runtest",runtest); } python ======================================= import ctopython def pfunc( ret ) print ret.long #how to get right from a C++ instance print ret.area() ctopython.runtest( pfunc ) #Pass parameters that is custom python object to c++ function ======================================= how to do?

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boost::python::iterator throws exception when using std::vector
by Andrew Marshall Nov. 11, 2012

Nov. 11, 2012

Hi there, I've just started using Boost::Python. I was following the example given in the tutorial regarding iterators at http://www.boost.org/doc/libs/1_52_0/libs/python/doc/tutorial/doc/html/pyth… I am attempting to fill a python::list from an std::vector with the following code, based on the snippet in the tutorial above: namespace py = boost::python; std::vector<int> v;v.push_back(1); py::object get_iterator = py::iterator<std::vector<int> >(); py::object iter = get_iterator(v); py::list l(iter); However the line "py::object iter = get_iter(v);" throws the following exception in python : TypeError: No to_python (by-value) converter found for C++ type: class std::vector<int,class std::allocator<int> > Any help would be appreciated. Thanks,Andrew. ----------------------------- Andrew Marshall http://www.planetmarshall.co.uk

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From python converter for builtin types
by Holger Brandsmeier Nov. 9, 2012

Nov. 9, 2012

Dear list, where does boost python define the from python converters for buildin types such as double / PyLong_Type? With the help of Changsheng Jiang I was able to modify builtin_converters.hpp and was able to change a to python converter for long double to produce numpy.float128. I do not find the place where the from python conversion is done, though. -Holger

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buildin converter for long double
by Holger Brandsmeier Nov. 7, 2012

Nov. 7, 2012

Dear list, the boost python buildin converter for long double: BOOST_PYTHON_TO_PYTHON_BY_VALUE(long double, ::PyFloat_FromDouble(x), &PyFloat_Type) converter/builtin_converters.hpp identifies long double, which on my system is a 128bit float, with a 64bit float in python. I would like to identify it with numpy`s float128. Can you give me any hings how I would be able to do that? -Holger

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