Mailman 3 February 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. 6, 2011

Aug. 6, 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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init< LPCTSTR > error if used in static member of same class
by AdrianB March 3, 2011

March 3, 2011

Anny Idea why following situation failes to compile? class A { public: A( LPCTSTR szParam ){}; ~A(){}; }; class B: public A { public: B( LPCTSTR szParam ) A(szParam){}; ~B(){}; static void includePyModuleDefinition(); }; void B::includePyModuleDefinition() { class_<B>("MyB", init< LPCTSTR >() ); } Compiler result is: error C2275: 'LPCTSTR' : illegal use of this type as an expression c:\program files\microsoft sdks\windows\v6.0a\include\winnt.h(391) : see declaration of 'LPCTSTR' error C2059: syntax error : ')' The eonly way to solve this issue by now are: - use no_init => not an option for me because I need the parameter - move the static member function out of the class B => unhappy because this would be a breach of my codeing std. for this module - remove the class inheritance for B to 'public A' The problem arises only if following three facts come togather: 1) inheritance from a base class 2) the includePyModuleDefinition() is a static member of the exposed class iteself 3) the init has to tale at least one param Regards, Adrian

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intercepting uncaught exceptions
by Gennadiy Rozental Feb. 27, 2011

Feb. 27, 2011

Hi, Is there any way to intercept uncaught exception in embedded Python code? I need to add some information to an exception/traceback in this case. I have full control over environment before embedded code is executed. I thought I'll be able to use sys.excepthook, but it does not seem to be invoked. Please advise, Gennadiy

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Can't add attribute to function
by Neal Becker Feb. 22, 2011

Feb. 22, 2011

I can add attributes to instances of classes created by boost::python, but not to boost::python functions: limiter.delay = 0 AttributeError: 'Boost.Python.function' object has no attribute 'delay' Any ideas?

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Creating a unicode instrance from utf-8 encoded string
by Wichert Akkerman Feb. 21, 2011

Feb. 21, 2011

I'm trying to do something which should be very simple, but I'm not having much luck figuring out how from the existing documentation. For a python 2 project I am trying to return a gettext-translated string as a unicode instance to python. The return value for gettext() is a UTF-8 encoded char*, which should be pretty simple to convert to a python unicode instrance using PyUnicode_FromString. I have a feeling this is trivial to do, but I can't seem to figure out how. Wichert.

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Boost.Python Metaclass
by James Emerton Feb. 16, 2011

Feb. 16, 2011

Given a C++ class wrapped with Boost.Python: class CPPClass { void test(); } BOOST_PYTHON_MODULE(testmodule) { class_<CPPClass>("CPPClass") .def("test", &CPPClass::test) ; } I've created a python subclass and redefined the metaclass: class Meta(CPPClass.__class__): def __new__(cls, name, bases, attrs): return super(Meta, cls).__new__(cls, name, bases, attrs) class PyClass(CPPClass): __metaclass__ = Meta Any attempt to call methods of PyClass, or to pass it as an argument to a C++ function results in an ArgumentError. It appears that ob_type is being tested for equivalence to the Boost.Python.class type. I am currently working around this by using a plain function as the metaclass, but it's not ideal as each base class must set the metaclass explicitly. I browsed through object/class.cpp, and I think using PyType_IsSubtype() in place of == &class_metatype_object should be sufficient to allow me to derive metaclasses from Boost.Python.class. Does anyone have any advice, comments or objections before I proceed? James

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C++ derived from bp::dict
by Michael Andronov Feb. 10, 2011

Feb. 10, 2011

Hi, Being a newbie to boost::python, I have a question ( hopefully simple), which failed to find the answer in mail logs: let's say a. I have a C++ class, derived from boost::python::dict ; b. I would like later to get access to myLong, and to the dictionary, my class derived from. Would mentioning the boost::python::dict as a base wtihin wrapping section be enough to get access to dictionary? (Something like... " .... class myd :boost::python::dict { ... public: unsigned long myLong; } BOOST_PYTHON_MODULE(mymod) { using namespace boost::python; class_<myd, bases<dict> > ("mydict") .def_readwrite("pd", &myd::pd); ... } Thanks. Michael.

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