Mailman 3 November 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.

4 6

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

4 4

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.

4 4

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

2 1

pygccxml and inner classes
by Davidson, Josh Nov. 29, 2010

Nov. 29, 2010

I'm wondering if this behavior is correct when using pygccxml. Consider the following two sets of simple class definitions: -------------- SET 1 ---------------------- class inner { protected: unsigned a; unsigned b; unsigned c; }; class Cool { public: Cool(){} protected: int x; int y; int z; inner i; }; -------------- SET 2 ---------------------- class Cool { public: Cool(); protected: class inner { protected: unsigned a; unsigned b; unsigned c; }; int x; int y; int z; inner i; }; -------------- END ---------------------- So you'll notice that the only difference between 1 & 2 is that 2, defines "inner" as an inner class. Now, if I parse a header file containing those classes, obtain a reference to the pygccxml for class Cool and print it's variables like so: for var in classType.variables(): print "var", var.name, var.type This is what I get: SET 1 var x int var y int var z int var i inner SET 2 var x int var y int var z int var i Cool::inner var a unsigned int var b unsigned int var c unsigned int As you can see, when I is an inner class, the inner class's members show up in the parent class in addition to the inner class itself. Is this behavior correct? In SET 2, I would not expect to see a, b, and c show up as members of class Cool. If this behavior is correct, is there a way to filter out those members that belong to the inner class?

2 1

Expose c++ class as python module
by Simon W Nov. 9, 2010

Nov. 9, 2010

Hi, I want to export my c++ class and make an instance of it and then expose it to python as if it were a python module. Is it possible? // export and create instance class_<myClass> [...]; namespace["instance"] = ptr( instanceOfMyClass ); Then in python: import instance instance.someFunction() Thank you! /Simon

2 1

boost::python executes wrong implementation
by AdrianB Nov. 8, 2010

Nov. 8, 2010

Hello The Situation: There are three modules involved: a) myapi.pyd b) myapi.dll c) myserver.dll myapi is a VC++ Project which exposes few classes and methods to python. myapi.pyd is a UNICODE build, to be used in python. myapi.dll is a ANSI build, to be used embedded by the myserver.dll myserver.dll runs python embedded, and links myapi.dll UseCase in Python: # ------------------ import myapi # myapi.pyd session = myapi.Session( <some credentials> ) # myapi.pyd::Session # at this moment myserver.dll gets loaded into the python process # along with its embedded python module, called "myembedded" import myembedded # myserver.dll embedded_session = myembedded.Session() # myapi.dll::Session #!! The ISSUE !! embedded_session.myEmbeddedImpl() # should call myapi.dll::Session::myEmbeddedImpl() # -- what happens? -- instead of executing myapi.dll::Session::myEmbeddedImpl() it executes myapi.pyd::Session::myEmbeddedImpl()!!! Why? And how can I avoid this? Anny idea and help is greatly appreciated, best regards, Adrian

2 3

2 "using python" declarations in user-config.jam not working
by John Reid Nov. 5, 2010

Nov. 5, 2010

Hi, I can't get boost.build configured for 2 different python versions, of which one is a debug build. I follow the instructions here: http://www.boost.org/doc/libs/1_44_0/libs/python/doc/building.html My user-config.jam has entries like this # default python - this picks up a standard Ubuntu 2.6 install using python ; # debug python build - this picks up my debug build from source using python : 2.7 : /home/john/local/python-dbg/bin/python2.7 : : : <python-debugging>on ; Unfortunately when I build my project bjam -q -j3 debug which is configured thus: project Proj : requirements <variant>debug:<python-debugging>on : usage-requirements : default-build debug ; It uses a boost.python built against the default python. This libboost_python.so.1.44.0 has an undefined symbol PyUnicodeUCS4_AsUTF8String. If I comment out the line in user-config.jam using python ; so that all my builds use the debug 2.7 python it works ok but presumably then I have a problem with release builds. This looks like a bug to me. How am I supposed to configure this in user-config.jam? Thanks, John.

1 1

Unable to find -lboost_python
by Aishwarya Venkataraman Nov. 5, 2010

Nov. 5, 2010

Hello, I want to install pydoop to get python talk to hadoop/ hdfs file system. This requires me to have boost installed. I have installed boost using macports. python setup.py build_ext -L/opt/local/lib/ -I/opt/local/include/ When I run the above command to install pydoop, it gives me the following error: g++ -L/Applications/djangostack-1.2.3-0/common/lib -bundle -undefined dynamic_lookup build/temp.macosx-10.4-i386-2.6/src/pipes.o build/temp.macosx-10.4-i386-2.6/src/pipes_context.o build/temp.macosx-10.4-i386-2.6/src/pipes_test_support.o build/temp.macosx-10.4-i386-2.6/src/pipes_serial_utils.o build/temp.macosx-10.4-i386-2.6/src/exceptions.o build/temp.macosx-10.4-i386-2.6/src/_pipes_main.o build/temp.macosx-10.4-i386-2.6/src/SerialUtils.o build/temp.macosx-10.4-i386-2.6/src/HadoopPipes.o build/temp.macosx-10.4-i386-2.6/src/StringUtils.o -L/opt/local/lib/ -lpthread *-lboost_python* -o build/lib.macosx-10.4-i386-2.6/pydoop/_pipes.so *ld: library not found for -lboost_python* Where exactly is lboost_python located on a mac? How do I find this library ? Thanks, Aishwarya

2 1

Python iterable to std map
by Charles Solar Nov. 3, 2010

Nov. 3, 2010

I have a class interface I expose to python that has methods such as begin, end, rbegin, rend. Its meant to be a class that C++ can iterate over. I now want to make the object defined in python, so python can pass the C++ library an object of python's class and C++ can use it like it would any real C++ object derived from the same interface. Since python does not really have a concept of begin, end, rbegin, rend, I thought a good idea would be to have the python class define a __iter__ method and use that method with stl_input_iterator to pull in the complete list from python to use with begin, end, etc. What I have currently is a python converter for tuples of size 2 to std pairs, then the wrapper class for the interface calls > struct IFooHolder_wrapper : IFooHolder, bp::wrapper< IFooHolder > > { > mutable std::map< std::string, boost::shared_ptr< IFoo > > _map; > const_iterator begin() const > { > std::copy( bp::stl_input_iterator< std::pair< std::string, boost::shared_ptr< IFoo > > >( bp::object( bp::handle<>( bp::borrowed( bp::detail::wrapper_base_::get_owner(*this) ) ) ) ), bp::stl_input_iterator< std::pair< std::string, boost::shared_ptr< IFoo > > >(), std::inserter( _map, _map.begin() ) ); > return _map.begin(); > } to copy all the iterations into a map the wrapper holds. Then the begin, end, rbegin, rend methods return iterations from that map. My main concern is firstly if there is a better way. More elegant solutions like the map indexing suite do not really work on this problem, and google can only help so much. I fear there is not much documentation from others trying to do the same thing. I especially do not like "bp::object( bp::handle<>( bp::borrowed( bp::detail::wrapper_base_::get_owner(*this) ) ) )" >From my understanding of stl_input_iterator, it needs a bp::object that has an "__iter__" attribute. I want to use this->get_override( "__iter__" ) but that does not work. So if someone knows a better way to build a bp::object from a bp::wrapper class that would be a good start. I should mention my solution compiles but does not work. Python crashes when it tries to do the std::copy Thanks for any input

1 0