Mailman 3 September 2009 - 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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Getting object for PyObject (reference counting)
by Murray Cumming Feb. 11, 2010

Feb. 11, 2010

I can't find any definitive documentation that tells me how I should get a boost::python::object to wrap an existing PyObject*. I guess that there's a way to do it that uses an existing reference, and a way that takes an extra reference. -- murrayc(a)murrayc.com www.murrayc.com www.openismus.com

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boost python to/from python type conversion
by James Amundson Oct. 1, 2009

Oct. 1, 2009

Hi, I'm trying to write to/from type converters for my code, and I'm stuck. My case doesn't map well to any of those in the boost python documentation. I'm trying to pass objects of type MPI_Comm (really a C type!) back and forth with mpi4py (which uses cython internally.) The mpi4py author has provided a working example using manual wrapping. I am attaching it to the end of this message. On the C++ side I can extract a point to the MPI_Comm object from a Python object like so: PyObject* py_obj; // obviously, the value of py_obj has to be set somewhere... MPI_Comm *comm_p = PyMPIComm_Get(py_obj); I thought it would be simple to write a type converter to do that, but I don't understand the mechanics. This example doesn't seem to map onto the lvalue_from_pytype paradigm, or the scitbx container_conversion paradigm. Any suggestions? Thanks, Jim Amundson ----------------------------------- // working example with manual conversion #include <mpi.h> #include <iostream> static void sayhello(MPI_Comm comm) { if (comm == MPI_COMM_NULL) { std::cout << "You passed MPI_COMM_NULL !!!" << std::endl; return; } int size; MPI_Comm_size(comm, &size); int rank; MPI_Comm_rank(comm, &rank); int plen; char pname[MPI_MAX_PROCESSOR_NAME]; MPI_Get_processor_name(pname, &plen); std::cout << "Hello, World! " << "I am process " << rank << " of " << size << " on " << pname << "." << std::endl; } #include <boost/python.hpp> #include <mpi4py/mpi4py.h> using namespace boost::python; static void hw_sayhello(object py_comm) { PyObject* py_obj = py_comm.ptr(); MPI_Comm *comm_p = PyMPIComm_Get(py_obj); if (comm_p == NULL) throw_error_already_set(); sayhello(*comm_p); } BOOST_PYTHON_MODULE(helloworld) { if (import_mpi4py() < 0) return; /* Python 2.X */ def("sayhello", hw_sayhello); }

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[Py++] Does pyplusplus respect explicit constructors?
by Christopher Bruns Oct. 1, 2009

Oct. 1, 2009

Single-argument C++ constructors in pyplusplus seem to generate a boost::python::implicitly_convertible tag, even when the constructor is declared "explicit" in C++. That doesn't sound right to me. Shouldn't a pair of types that are not implicitly convertible in C++, also not be implicitly convertible in python? I suspect I can manually adjust the implicitly_convertible tag generation using the "allow_implicit_conversion" flag in pyplusplus. Is there a way to tell pyplusplus to avoid generating an implicitly_convertible tag for all explicit constructors? ########## test.h input source ############ class Foo { public: Foo() {} }; class Bar { public: // explicit constructor means don't implicitly convert Foo to Bar in C++ explicit Bar(Foo&) {} }; ############################### ########## wrap.py wrapping code #### from pyplusplus import module_builder mb = module_builder.module_builder_t(["test.h"] , gccxml_path = "C:\\Program Files\\gccxml_sherm\\bin\\gccxml.exe") mb.build_code_creator( module_name='test' ) mb.write_module( 'test_explicit.cpp' ) ################################## ##### generated test_explicit.cpp ###### // This file has been generated by Py++. #include "boost/python.hpp" #include "test.h" namespace bp = boost::python; BOOST_PYTHON_MODULE(test){ { //::Bar typedef bp::class_< Bar > Bar_exposer_t; Bar_exposer_t Bar_exposer = Bar_exposer_t( "Bar", bp::init< Foo & >(( bp::arg("arg0") )) ); bp::scope Bar_scope( Bar_exposer ); bp::implicitly_convertible< Foo &, Bar >(); // <-- *** I'm surprised by this *** } bp::class_< Foo >( "Foo", bp::init< >() ); } ##################################

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Anyone have Py++ working on a Mac?
by Randolph Fritz Sept. 30, 2009

Sept. 30, 2009

As the title says.

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Installing Boost VC9.0Express and Python 2.5.2 - import PYD complains about python26.dll!!??
by Bob Cumming Sept. 29, 2009

Sept. 29, 2009

Hello, I'm new to this list and have been trying to install boost to workk with C++ code in python. I downloaded the boost 1.39 windows installer and that worked ok. I followed the tutorials I found online at boost and the python wiki. All seemed to go ok. In directory: C:\boost\boost_1_39\libs\python\example\tutorial command bjam --preserve-test-target However I tried to run the hello example, at first I got the erros about the boost_python-vc90-mt-1_39.dll files so I copied them to the output directory, so I cd to the directory, then launch python and try to import the pyd file. I get the error (message box) "The application has failed to start because python26.dll was not found. Re-installing the applicaiton may fix this problem" Recall I have python 2.5.2 installed!? I tried re-running the bjam command and I get this: ...patience... ...found 1279 targets... ...updating 2 targets... capture-output bin\hello.test\msvc-9.0express\debug\threading-multi\hello ====== BEGIN OUTPUT ====== Traceback (most recent call last): File "hello.py", line 6, in <module> import hello_ext ImportError: DLL load failed: The specified module could not be found. EXIT STATUS: 1 ====== END OUTPUT ====== set Path=C:\Python25;C:\Python25\libs;C:\boost\boost_1_39\bin.v2\libs\python\build\msvc-9.0express\debug\threading-multi;C:\boost\boost_1_39\libs\python\example\tutorial\bin\msvc-9.0express\debug\threading-multi;%Path% set PYTHONPATH=bin\msvc-9.0express\debug\threading-multi "C://Python25\python" "hello.py" > "bin\hello.test\msvc-9.0express\debug\threading-multi\hello.output" 2>&1 set status=%ERRORLEVEL% echo. >> "bin\hello.test\msvc-9.0express\debug\threading-multi\hello.output" echo EXIT STATUS: %status% >> "bin\hello.test\msvc-9.0express\debug\threading-multi\hello.output" if %status% EQU 0 ( copy "bin\hello.test\msvc-9.0express\debug\threading-multi\hello.output" "bin\hello.test\msvc-9.0express\debug\threading-multi\hello" ) set verbose=0 if %status% NEQ 0 ( set verbose=1 ) if %verbose% EQU 1 ( echo ====== BEGIN OUTPUT ====== type "bin\hello.test\msvc-9.0express\debug\threading-multi\hello.output" echo ====== END OUTPUT ====== ) exit %status% ...failed capture-output bin\hello.test\msvc-9.0express\debug\threading-multi\hello... ...failed updating 1 target... ...skipped 1 target... C:\boost\boost_1_39\libs\python\example\tutorial>bjam --preserve-test-target ...patience... ...found 1279 targets... ...updating 2 targets... capture-output bin\hello.test\msvc-9.0express\debug\threading-multi\hello ====== BEGIN OUTPUT ====== Traceback (most recent call last): File "hello.py", line 6, in <module> import hello_ext ImportError: DLL load failed: The specified module could not be found. EXIT STATUS: 1 ====== END OUTPUT ====== set Path=C:\Python25;C:\Python25\libs;C:\boost\boost_1_39\bin.v2\libs\python\build\msvc-9.0express\debug\threading-multi;C:\boost\boost_1_39\libs\python\example\tutorial\bin\msvc-9.0express\debug\threading-multi;%Path% set PYTHONPATH=bin\msvc-9.0express\debug\threading-multi "C://Python25\python" "hello.py" > "bin\hello.test\msvc-9.0express\debug\threading-multi\hello.output" 2>&1 set status=%ERRORLEVEL% echo. >> "bin\hello.test\msvc-9.0express\debug\threading-multi\hello.output" echo EXIT STATUS: %status% >> "bin\hello.test\msvc-9.0express\debug\threading-multi\hello.output" if %status% EQU 0 ( copy "bin\hello.test\msvc-9.0express\debug\threading-multi\hello.output" "bin\hello.test\msvc-9.0express\debug\threading-multi\hello" ) set verbose=0 if %status% NEQ 0 ( set verbose=1 ) if %verbose% EQU 1 ( echo ====== BEGIN OUTPUT ====== type "bin\hello.test\msvc-9.0express\debug\threading-multi\hello.output" echo ====== END OUTPUT ====== ) exit %status% ...failed capture-output bin\hello.test\msvc-9.0express\debug\threading-multi\hello... ...failed updating 1 target... JAMROOT: # Copyright David Abrahams 2006. Distributed under the Boost # Software License, Version 1.0. (See accompanying # file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) # Specify the path to the Boost project. If you move this project, # adjust this path to refer to the Boost root directory. use-project boost : C:/boost/boost_1_39 ; # Set up the project-wide requirements that everything uses the # boost_python library from the project whose global ID is # /boost/python. project : requirements <library>/boost/python//boost_python ; # Declare the three extension modules. You can specify multiple # source files after the colon separated by spaces. python-extension hello_ext : hello.cpp ; # A little "rule" (function) to clean up the syntax of declaring tests # of these extension modules. local rule run-test ( test-name : sources + ) { import testing ; testing.make-test run-pyd : $(sources) : : $(test-name) ; } # Declare test targets run-test hello : hello_ext hello.py ; user-config # MSVC configuration using msvc : 9.0express ; # Python configuration using python : 2.5 : C://Python25 ; Sorry if this is a very long message, but thought more info should help the understanding. I have done this on two PC's, and got the same results.... Can anyone suggest any ideas on how to get this to work? Thanks for reading and any advice greatefully recieved. Cheers _________________________________________________________________ Get the best of MSN on your mobile http://clk.atdmt.com/UKM/go/147991039/direct/01/

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Boost Python objects and object identity
by Pertti Kellomäki Sept. 29, 2009

Sept. 29, 2009

I have Python bindings for a C++ library that among other things contains classes for describing the static structure of a microprocessor. My background is in Lisp, so I am used to using object identities (references) as keys. The C++ library can be used in this fashion, e.g. looking up a register file by name always returns the same object reference. However, the C++ to Python mapping does not preserve object identity, as a new Python object is created for every query, even if the underlying C++ reference is the same. Is there any easy way to preserve object identity in this sense with Boost Python? My first thought was to use some kind of caching scheme so that consequent queries with a particular name return the same object, but the problem is that objects are not only looked up by name, they can also be returned e.g. by asking for a parent object in a containment hierarchy. -- Pertti

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[Py++] Help with wrapping setter methods
by Christopher Bruns Sept. 29, 2009

Sept. 29, 2009

Please help. I am just a beginner with pyplusplus and am not smart enough to see how to create certain complex rules. How would I create a pyplusplus rule for setting the return policy to "return internal reference" for all member functions that meet the following criteria: * method name begins with "set" * return type is a reference to the parent class or to one of its base classes I would sincerely appreciate an example that could do this. Then perhaps I might be able to figure out how to perform other clever manipulations. Thanks in advance for your help. ################################# struct Foo { // example of the sort of method I mean Foo& setBaz(int baz); // returns reference to self }; ################################# from pyplusplus import module_builder from pyplusplus.module_builder.call_policies import * mb = module_builder(...) # want "something" below... mb.decls(<something?>).call_policies = return_internal_reference() ################################# --Chris Bruns

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