Mailman 3 April 2010 - 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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Problems with boost tuples to python conversion
by Maciej Sitarz April 30, 2010

April 30, 2010

Hi, I tried to expose objects of class: typedef boost::tuple<ClassA, std::string> RegisterResult; to python. I used automatic conversion (http://www.language-binding.net/pyplusplus/troubleshooting_guide/automatic_…) but as usual I hit a wall and got unsolvable error. INFO gccxml cmd: /usr/bin/gccxml -I"." -I"/home/macieks/error_examples/boost_tuples_to_python" -I"/usr/include" -I"/usr/include/python2.4" -I"/home/macieks/boost/boost_1_42_0" "test.h" -fxml="/tmp/tmp9Kp4rg.xml" Traceback (most recent call last): File "generate.py", line 14, in ? indexing_suite_version=2 File "usr/lib/python2.4/site-packages/pyplusplus/module_builder/boost_python_builder.py", line 95, in __init__ File "usr/lib/python2.4/site-packages/pyplusplus/module_builder/boost_python_builder.py", line 138, in __parse_declarations File "usr/lib/python2.4/site-packages/pygccxml/parser/project_reader.py", line 217, in read_files File "usr/lib/python2.4/site-packages/pygccxml/parser/project_reader.py", line 242, in __parse_file_by_file File "usr/lib/python2.4/site-packages/pygccxml/parser/source_reader.py", line 206, in read_file File "usr/lib/python2.4/site-packages/pygccxml/parser/source_reader.py", line 231, in read_gccxml_file pygccxml.parser.source_reader.gccxml_runtime_error_t: Error occured while running GCC-XML: /home/macieks/boost/boost_1_42_0/boost/mpl/bool_fwd.hpp:21: sorry, unimplemented: call_expr cannot be mangled due to a defect in the C++ ABI I tried to use tuples.hpp from pyogre (it has some few lines added), but the problem is the same. I attached simple example files to this mail. Best regards -- Maciek Sitarz

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boost graph bgl-python on MAC OS X 10.6.3
by Andrew Schweitzer April 28, 2010

April 28, 2010

Hi, I'm trying to use the bgl-python library which exposes boost's graph library ('bgl') to python. Has anyone built this recently for MAC OS X? I tried versions bgl-python.0.9 and svn-HEAD. I got different errors in both cases. I suspect I'm doing something obvious wrong. Here is what I got from svn-HEAD: ../boost_1_42_0/bjam installwarning: No toolsets are configured. warning: Configuring default toolset "gcc". warning: If the default is wrong, your build may not work correctly. warning: Use the "toolset=xxxxx" option to override our guess. warning: For more configuration options, please consult warning: http://boost.org/boost-build2/doc/html/bbv2/advanced/configuration.html notice: could not find main target install notice: assuming it is a name of file to create. /Users/schweitz/Documents/misc/boost/boost_1_42_0/tools/build/v2/build/project.jam:740: in attribute warning: rulename $($(project).attributes).get expands to empty string /Users/schweitz/Documents/misc/boost/boost_1_42_0/tools/build/v2/build/project.jam:752: in project.target ... /Users/schweitz/Documents/misc/boost/boost_1_42_0/boost-build.jam:17: in module scope don't know how to make <e>install ...found 1 target... ...can't find 1 target... Any ideas? Thanks Andrew

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Re: [C++-sig] boost::python::len( list_object) throws "Access violation" (MSDev v9/Boost 1.41)
by John McLaughlin April 26, 2010

April 26, 2010

I believe I have found my problem. I was allowing the GIL to be released (essentially letting multiple threads run concurrently) but the " const boost::python::list & disks" argument was not protected at this point. I can either move the Py_BEGIN_ALLOW_THREADS call to after I am finished accessing the "disks" arg, or use Py_BLOCK_THREADS and Py_UNBLOCK_THREADS to protect access calls. John John McLaughlin iStor Networks, Inc. -----Original Message----- From: John McLaughlin Sent: Friday, April 23, 2010 8:01 PM To: 'cplusplus-sig(a)python.org.' Subject: boost::python::len( list_object) throws "Access violation" (MSDev v9/Boost 1.41) I have a strange crash in my C++ method when called from Python. I have a method that has one of the arguments a Python List. The symptoms are the same with an empty list and a non-empty one. In one method, early in the code I call; boost::python::len( var ) and it returns properly. HOWEVER, in another method, I am passing the *same value* from Python, but the "boost::python::len( var )" aborts when "PyErr_Occurred()" is called. It causes an access violation (like a bad pointer dereference). What is strange is that the line before (calling PyObject_Length(obj.ptr() ) returns a proper size. Any ideas? ------------------------------------------------------ namespace boost { namespace python { inline ssize_t len(object const& obj) { ssize_t result = PyObject_Length(obj.ptr()); if (PyErr_Occurred()) throw_error_already_set(); return result; } }} // namespace boost::python ------------------------------------------------------ void PyService_Volume::Reconfigure( const PyStorageSize & sizeInBytes, const iStor::UserAgent::UAEnums::VolumeCompositionName & compositionName, const boost::python::list & disks, int stripeWidth, const iStor::UserAgent::UAEnums::StripeDepth & stripeDepth) { Py_BEGIN_ALLOW_THREADS . . . if (boost::python::len(disks) > 0) { ... ------------------------------------------------------ John McLaughlin iStor Networks, Inc.

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Catching Boost.Python.ArgumentError
by Austin Bingham April 26, 2010

April 26, 2010

I feel like I'm missing something simple, but how do I catch Boost.Python.ArgumentException? As far as I can tell, the Boost.Python module is not something I can import explicitly, so I can't write "catch Boost.Python.ArgumentException:". I can do something like comparing type and module name strings, but that just feels inelegant and a trouble for maintenance. Any ideas would be very welcome. Austin

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boost::python::len( list_object) throws "Access violation" (MSDev v9/Boost 1.41)
by John McLaughlin April 24, 2010

April 24, 2010

I have a strange crash in my C++ method when called from Python. I have a method that has one of the arguments a Python List. The symptoms are the same with an empty list and a non-empty one. In one method, early in the code I call; boost::python::len( var ) and it returns properly. HOWEVER, in another method, I am passing the *same value* from Python, but the "boost::python::len( var )" aborts when "PyErr_Occurred()" is called. It causes an access violation (like a bad pointer dereference). What is strange is that the line before (calling PyObject_Length(obj.ptr() ) returns a proper size. Any ideas? ------------------------------------------------------ namespace boost { namespace python { inline ssize_t len(object const& obj) { ssize_t result = PyObject_Length(obj.ptr()); if (PyErr_Occurred()) throw_error_already_set(); return result; } }} // namespace boost::python ------------------------------------------------------ void PyService_Volume::Reconfigure( const PyStorageSize & sizeInBytes, const iStor::UserAgent::UAEnums::VolumeCompositionName & compositionName, const boost::python::list & disks, int stripeWidth, const iStor::UserAgent::UAEnums::StripeDepth & stripeDepth) { Py_BEGIN_ALLOW_THREADS . . . if (boost::python::len(disks) > 0) { ... ------------------------------------------------------ John McLaughlin iStor Networks, Inc.

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Boost.Python Constructor Issue
by Zach Elko April 22, 2010

April 22, 2010

Hello all, Forgive me if this isn't the proper forum for this, but I'm having the following issue: http://codepad.org/EFPnkIUm System info (Boost is a tad outdated at the moment): Boost.Jam Version 3.1.16. OS=LINUX. BOOST_VERSION 103700 Python 2.6.1 Any help is greatly appreciated, thanks! Zach J. Elko

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Re: [C++-sig] Status of Numpy support in boost python
by Hans Meine April 22, 2010

April 22, 2010

Am Montag 08 März 2010 13:32:22 schrieb Pim Schellart: > we are working on a project for which it would be extremely useful if > numpy arrays could be passed as arguments to wrapped C++ methods. > On the website I cannot find any evidence that this is currently > supported by Boost Python. > Is this (or will this be) implemented? After all the recent discussion, I want to point to yet another (hopefully) interesting bit of code which I am involved with: Our "vigra" (computer vision) library now comes with numpy- and BPL-based python bindings. In addition to type-safe conversions between C++ and Python(*), this offers a vigra::MultiArray on the C++ side, which is an n-dimensional array class template, complete with n-dimensional iterators (using raw pointers for the innermost dimension to offer the best possible performance for unstrided arrays) and a lot of algorithms, i.e. pointwise transformation / [possibly type-coercing] copying / inspection etc. One particular feature Ulli is proud of is the automatic conversion to *subclasses* of ndarray, such that we can register and use e.g. 'Volume' python classes for 3D arrays. I really want to stress that VIGRA is a very versatile template library which should be able to work in conjunction with any other libraries and data structures, i.e. true generic code (usually you don't even need to compile VIGRA, if you are not interested in an image import/export library). So don't hesitate to give it a shot even if you are /not/ interested in any of its array / linalg algorithms. (Actually, the PythonArray template class should be even useful without boost::python, i.e. I am using it with SIP, too.) I don't think there will ever be just /one/ single solution for boost::python+numpy, since everyone seems to have different requirements/expectations w.r.t. available algorithms, static vs. dynamic element types etc. However, I do think that our vigranumpy approach could be very useful for some of this list's readers. HTH, Hans

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