Mailman 3 March 2014 - 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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Exposing a generic template system in Boost.Python
by Francesco Biscani March 20, 2014

March 20, 2014

Greetings, I have been trying to think of a solution about this for a few days now, but I did not get very far. I am exposing specific instances of C++ template classes using Boost.Python. Let's say for the sake of argument that I am exposing std::vector<of-a-few-types>. What I would like to achieve on the Python side would be some kind of unified interface of this kind: # Define a vector-of-ints type. vec_int = vector["int"] # Define a vector-of-doubles type. vec_float = vector["double"] ... etc., possibly with exceptions being raised if a template type which has not been exposed is requested. Additionally, the system should automagically work with nested generic types: # Define a vector-of-vectors-of-ints type. vec_vec_int = vector[vector["int"]] I have played around with some ideas, but it seems like I can never get to a point where the design does not look bloated and/or brittle. Thus I am wondering, is there anyone that tackled a problem like this before in Boost.Python and has pointers/suggestions on how to do this properly? Support for things like default template arguments would definitely be a plus. FWIW, I have access to C++11 on the C++ side, so I can deal with variadic templates and other amenities in a not-so-kludgy way. Thanks for any input, Francesco.

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How to wrap class enums
by Deepankar Sharma March 12, 2014

March 12, 2014

Any pointers on how to expose class enums to Python? Given the following enum what would the boost code to expose it to python look like? The page at http://www.boost.org/doc/libs/1_55_0/libs/python/doc/v2/enum.html only lists examples of old style enums. enum class t_functions { ADD, SUB, MUL, DIV };

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Installation of boost.python using boost 1.55.0
by Raghvendra Jain March 8, 2014

March 8, 2014

Hi all, I've setup the PATH for C:\Python27, and execute the 'bootstrap' in the boost folder. The error message displayed: Building Boost.Build engine "VCVARS32.BAT" is not recognized as commands or executable programs/bat file. What should I do ? Best Regards, Raghav On Sun, Mar 2, 2014 at 8:30 AM, Kevin Kunzmann <kevinkunzmann(a)gmx.net>wrote: > Hi! > > I just successfully built boost using bootstrap and .\b2 on Windows 8.1 > with msvc 11.0. I put it in C:\local\boost_1_55_0 > > In my home directory I created user-config.jam: > > # MSVC configuration > using msvc : 11.0 ; > > # Python configuration > using python : : C:/Users/Kevin/Anaconda ; > > as I use the anaconda python distribution. It seems to recognize it, as I > do not get any ojections when invoking bjam in > C:\local\boost_1_55_0\libs\python\example\tutorial, here is the complete > output: > > C:\local\boost_1_55_0\libs\python\example\tutorial>bjam > link.jam: No such file or directory > ...patience... > ...patience... > ...found 1678 targets... > ...updating 14 targets... > common.mkdir bin > common.mkdir bin\msvc-11.0 > common.mkdir bin\msvc-11.0\debug > compile-c-c++ bin\msvc-11.0\debug\hello.obj > hello.cpp > msvc.link.dll bin\msvc-11.0\debug\hello_ext.pyd > LINK : fatal error LNK1104: cannot open file > 'boost_python-vc110-mt-gd-1_55.lib' > > > call "C:\Program Files (x86)\Microsoft Visual Studio > 11.0\vc\vcvarsall.b > at" x86 >nul > link /NOLOGO /INCREMENTAL:NO /DLL /DEBUG /MACHINE:X86 /MANIFEST > /subsystem:conso > le /out:"bin\msvc-11.0\debug\hello_ext.pyd" > /IMPLIB:"bin\msvc-11.0\debug\hello_e > xt.lib" /LIBPATH:"C:\Users\Kevin\Anaconda\libs" > @"bin\msvc-11.0\debug\hello_ex > t.pyd.rsp" > if %ERRORLEVEL% NEQ 0 EXIT %ERRORLEVEL% > > ...failed msvc.link.dll bin\msvc-11.0\debug\hello_ext.pyd > bin\msvc-11.0\debug\he > llo_ext.lib bin\msvc-11.0\debug\hello_ext.pdb > bin\msvc-11.0\debug\hello_ext.pdb. > .. > common.copy boost_python-vc110-gd-1_55.dll > > ..\..\..\..\bin.v2\libs\python\build\msvc-11.0\debug\boost_python-vc110-gd-1_55. > dll > 1 Datei(en) kopiert. > ...skipped <p.>hello_ext.pyd for lack of > <pbin\msvc-11.0\debug>hello_ext.pyd... > common.mkdir bin\hello.test > common.mkdir bin\hello.test\msvc-11.0 > common.mkdir bin\hello.test\msvc-11.0\debug > ...skipped <pbin\hello.test\msvc-11.0\debug>hello for lack of > <pbin\msvc-11.0\de > bug>hello_ext.pyd... > ...failed updating 3 targets... > ...skipped 3 targets... > ...updated 8 targets... > > C:\local\boost_1_55_0\libs\python\example\tutorial> > > what went wrong here? what is link.jam and where do I get it from? > > best, > > Kevin > > _______________________________________________ > Cplusplus-sig mailing list > Cplusplus-sig(a)python.org > https://mail.python.org/mailman/listinfo/cplusplus-sig >

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getting the tutorial up and running
by Kevin Kunzmann March 4, 2014

March 4, 2014

Hi! I just successfully built boost using bootstrap and .\b2 on Windows 8.1 with msvc 11.0. I put it in C:\local\boost_1_55_0 In my home directory I created user-config.jam: # MSVC configuration using msvc : 11.0 ; # Python configuration using python : : C:/Users/Kevin/Anaconda ; as I use the anaconda python distribution. It seems to recognize it, as I do not get any ojections when invoking bjam in C:\local\boost_1_55_0\libs\python\example\tutorial, here is the complete output: C:\local\boost_1_55_0\libs\python\example\tutorial>bjam link.jam: No such file or directory ...patience... ...patience... ...found 1678 targets... ...updating 14 targets... common.mkdir bin common.mkdir bin\msvc-11.0 common.mkdir bin\msvc-11.0\debug compile-c-c++ bin\msvc-11.0\debug\hello.obj hello.cpp msvc.link.dll bin\msvc-11.0\debug\hello_ext.pyd LINK : fatal error LNK1104: cannot open file 'boost_python-vc110-mt-gd-1_55.lib' call "C:\Program Files (x86)\Microsoft Visual Studio 11.0\vc\vcvarsall.b at" x86 >nul link /NOLOGO /INCREMENTAL:NO /DLL /DEBUG /MACHINE:X86 /MANIFEST /subsystem:conso le /out:"bin\msvc-11.0\debug\hello_ext.pyd" /IMPLIB:"bin\msvc-11.0\debug\hello_e xt.lib" /LIBPATH:"C:\Users\Kevin\Anaconda\libs" @"bin\msvc-11.0\debug\hello_ex t.pyd.rsp" if %ERRORLEVEL% NEQ 0 EXIT %ERRORLEVEL% ...failed msvc.link.dll bin\msvc-11.0\debug\hello_ext.pyd bin\msvc-11.0\debug\he llo_ext.lib bin\msvc-11.0\debug\hello_ext.pdb bin\msvc-11.0\debug\hello_ext.pdb. .. common.copy boost_python-vc110-gd-1_55.dll ..\..\..\..\bin.v2\libs\python\build\msvc-11.0\debug\boost_python-vc110-gd-1_55. dll 1 Datei(en) kopiert. ...skipped <p.>hello_ext.pyd for lack of <pbin\msvc-11.0\debug>hello_ext.pyd... common.mkdir bin\hello.test common.mkdir bin\hello.test\msvc-11.0 common.mkdir bin\hello.test\msvc-11.0\debug ...skipped <pbin\hello.test\msvc-11.0\debug>hello for lack of <pbin\msvc-11.0\de bug>hello_ext.pyd... ...failed updating 3 targets... ...skipped 3 targets... ...updated 8 targets... C:\local\boost_1_55_0\libs\python\example\tutorial> what went wrong here? what is link.jam and where do I get it from? best, Kevin

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as_to_python_function and abstract C++ classes
by Andy Schneider March 3, 2014

March 3, 2014

Hi, Since I upgraded to gcc 4.8 I can no longer use as_to_python_function<T, C> with T being a type that's abstract (i.e. has >= 1 pure virtual method). This is because in gcc 4.8 the following: template <class U> static void convert_function_must_take_value_or_const_reference(U(*)(T), int, T* = 0) {} fails to compile since T is not constructible. Is this a known issue? Is there interest in a fix for this or are there are better ways to be constructing conversion functions in a typesafe manner in Boost.Python? Kind regards, Andy

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