Mailman 3 February 2009 - Cplusplus-sig

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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Bug and patch for boost.python with enable_shared_from_this
by Chad Austin March 26, 2009

March 26, 2009

Hi all, A month ago or so we discovered a bug in Boost.Python that manifests when using enable_shared_from_this. Here is a test case that demonstrates the bug: #include <boost/python.hpp> #include <boost/enable_shared_from_this.hpp> using namespace boost; using namespace boost::python; class Test; typedef shared_ptr<Test> TestPtr; class Test : public enable_shared_from_this<Test> { public: static TestPtr construct() { return TestPtr(new Test); } void act() { TestPtr kungFuDeathGrip(shared_from_this()); } void take(TestPtr t) { } }; void Export_test() { class_<Test, TestPtr, noncopyable>("Test") .def("construct", &Test::construct) .staticmethod("construct") .def("act", &Test::act) .def("take", &Test::take) ; } And here is the Python: x = Test.construct() x.take(x) x.act() The bug (as I understand it) is that the shared_ptr_from_python converter creates a new shared_ptr for the Test instance to pass it into C++. This new shared_ptr has a nop deleter, except that it keeps the Python object alive as long as the new shared_ptr is alive. The problem here is that creating a shared_ptr to an object of type T when T is enable_shared_from_this<T> resets the weak pointer inside of enable_shared_from_this<T>. (See shared_ptr's constructors for the details of the implementation.) A fix that passes the test above and has worked for us is to change shared_ptr's constructor to accept a dont_enable_shared_from_this argument and pass that in from the shared_ptr_from_python converter. The patch is attached (against boost 1.33, but the bug didn't look fixed in 1.34 either). Cheers, Chad p.s. I have seen other people with this problem as well. Googling for bad_weak_ptr turns up several results.

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Boost.Python app keeps crashing in debug
by Martin Walser March 15, 2009

March 15, 2009

Hi! :) I'm on the best way to become completely insane. I'm trying to set up VS2005 to run Boost Python in debug mode. Sorry for the long text... Problem summary: - applications crash in debug mode - dependencies to python25_d.dll AND python25.dll in boost_python-vc80-mt-gdy-1_35.dll - normal?? Only today I found out that I have to pass a special parameter to REALLY get a debug version. So I went into .\boost_1_35_0\libs\python\example\quickstart and called bjam with: bjam toolset=msvc --verbose-test test python-debugging=on Finally I got my boost_python-vc80-mt-gdy-1_35.dll & .lib files. Yet, simply defining BOOST_DEBUG_PYTHON & BOOST_ALL_NO_LIB in the header didn't work out. Had to put them in the preprocessor to make VC8 use the ...-gdy-... lib instead of the ...-gd-... lib. And to make him stop importing Python25.lib instead of python25_d.lib when building my .pyd C extension. Finally I found out that I have to add a _d to my extension filename as well so that python_d.exe finds the class I want to import. But now... my application crashes right after starting. Even the HelloWorld application from the tutorial crashes instantly: Unhandled exception at ... in python_d.exe And the debugger points to boost_1_35_0\libs\python\src\object\class.cpp's: [...] BOOST_PYTHON_DECL type_handle class_type() { if (class_type_object.tp_dict == 0) { class_type_object.ob_type = incref(class_metatype().get()); class_type_object.tp_base = &PyBaseObject_Type; =>!!! if (PyType_Ready(&class_type_object)) return type_handle(); // class_type_object.tp_setattro = class_setattro; } return type_handle(borrowed(&class_type_object)); } [...] Additionally, when putting boost_python-vc80-mt-gdy-1_35.dll in dependency walker I find dependencies to python25_d.dll AND python25.dll in it. I temporarily deleted python25.lib for testing ... and indeed, bjam demands python25.lib when building. Screenshot: http://i41.tinypic.com/2551g5j.jpg I hope someone with more experience got a clue... I'm lost. :( Thanks, Martin

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[c++-sig] Making a Python tuple from a Boost.Fusion sequence
by Bruno Lalande March 11, 2009

March 11, 2009

Hello, The topic below was opened in the Boost development mailing list, where it's been pointed out to me that it fits better here. You can also read the thread archive: http://thread.gmane.org/gmane.comp.lib.boost.devel/186573 Regards Bruno ---------- Forwarded message ---------- Hello, I have written a little function that converts any Boost.Fusion sequence into a Python tuple (boost::python::tuple). If a sub-sequence is nested in the sequence, the result will also be a nested tuple (for instance, boost::make_tuple(0, std::make_pair(1, 2), 3) will give (0, (1, 2), 3) in Python). The source code is attached to this mail. The principle is that any sequence previously adapted to Boost.Fusion will become a tuple in Python. So, by including the right boost/fusion/adapted/xxx header, one can convert a pair, a tuple, a boost::array, and obviously any of the sequences provided by Boost.Fusion. For example: #include <boost/python.hpp> #include <boost/fusion/adapted/std_pair.hpp> #include <boost/fusion/adapted/boost_tuple.hpp> #include <boost/fusion/container/generation/make_vector.hpp> #include "make_tuple_from_fusion_sequence.hpp" using namespace boost::python; tuple from_sequence() { return make_tuple_from_fusion( boost::fusion::make_vector( 1, std::make_pair("first", "second"), 2, boost::make_tuple('a', 'b', 'c'), 3 ) ); } BOOST_PYTHON_MODULE(mymodule) { def("from_sequence", &from_sequence); } In Python we get: >>> import mymodule >>> mymodule.from_sequence() (1, ('first', 'second'), 2, ('a', 'b', 'c'), 3) Is there any interest in adding this function into Boost.Python? If yes, I can write the doc and tests, clean the source and maybe improve the implementation (for example, I feel that I could avoid the use of m_iteration with a better use of Boost.Fusion...). Regards Bruno

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py++ boost::python::object
by Борис Казаков Feb. 26, 2009

Feb. 26, 2009

Hi I't trying to parse relatevely simple file with py++ (pyplusplus_gui): here is header file: #pragma once #include <boost/python.hpp> typedef boost::python::object pyobject; pyobject gaussian_diffs(pyobject imarray, double sigma); It fails with plenty of errors: Error occured during code generation process! Error: Error occured while running GCC-XML: In file included from /usr/include/boost/type_traits/composite_traits.hpp:17, from /usr/include/boost/function/function_base.hpp:24, from /usr/include/boost/function/detail/prologue.hpp:17, from /usr/include/boost/function/function_template.hpp:13, from /usr/include/boost/function/detail/maybe_include.hpp:13, from /usr/include/boost/function/function0.hpp:11, from /usr/include/boost/python/errors.hpp:13, from /usr/include/boost/python/handle.hpp:11, from /usr/include/boost/python/args_fwd.hpp:10, from /usr/include/boost/python/args.hpp:10, from /usr/include/boost/python.hpp:11, from /home/borsh/workspace/pyitk/gaussian_diffs.hxx:2: and much more. Is this excpected behaviour or should I try to update something? I'm using gccxml-cvs 20081124 pygccxml 1.0.0 py++ 1.0.0 boost 1.37. Thanks, Boris.

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[] subscript notation with boost::python
by Murray Cumming Feb. 24, 2009

Feb. 24, 2009

I'm trying to support this notation in python: something = record["somefieldname"] I had that working with the Python C API, by implementing the len and getitem functions, setting them in the PyTypeObject::tp_as_mapping struct field. I'm now trying to do this with boost::python, like so, because googling has suggested that this should work: boost::python::class_<Glom::PyGlomRecord>("Record") .def("__getitem__", &Glom::PyGlomRecord::getitem) .def("__len__", &Glom::PyGlomRecord::len) But when I try to use that in Python, I get this error: "Boost.Python.class' object is unsubscriptable" Is there something else that I need to do? -- Murray Cumming murrayc(a)murrayc.com www.murrayc.com www.openismus.com

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2 very interesting projects - Python / Finance
by David Russell Feb. 17, 2009

Feb. 17, 2009

Dear Python Group, First of all sorry for the unsolicited email, I have attached two very interesting long term Python projects in the Frankfurt area, Financial industry. I am working exclusively with the client on both requirements, interviews and contracts can be arranged very quickly. You will be involved in a project to develop the next generation of financial trading systems, this will be the biggest, fastest trading system of its kind in the world and will be used on a global scale. Financial experience is not a must, they are looking more for technical skills here. If the projects look interesting to you please feel free to contact me on the contact details below. Thank you for your help, Best Regards David Large Financial Institution - Frankfurt Senior Python C/C++ Developer (f/m) Tasks/Responsibilities Software developer for a complex electronic trading system. The software developer will work in the implementation team of the trading system; tasks include: - Requirements Analysis - Development of a Scripting framework based on Python - Specification - Implementation Target platform will be Linux. Qualifications/Required Skills (Mandatory) Rock Solid Python and C/C++ knowledge Integration of Python with C/C++ libraries Automated Testing Good overview and knowledge of open source software Experience of software development in large projects Good communications skills Ability to work in project teams A good command of English is a must. Additional Domain & Business Skills Knowledge of derivatives trading an advantage, in particular U.S. options. Additional Information: Frankfurt am Main, Germany Start ASAP for a minimum of 6 months Rate - Negotiable This is an urgent requirement please contact me or send me your cv as soon as possible. Contact: David Russell - Account manager email: david.russell(a)fdmgroup.com Tel: +49 (0) 69 756 0050 Web: www.fdmgroup.com //////////////////////////////////////////////////////////////////////// /// Large Financial Institution - Frankfurt am Main Performance / High Availability Test Automation Engineer (f/m) Tasks/Responsibilities Developer of automated test procedures for a high-performance electronic trading system. The engineer will work in the Performance and Technical Test team of the project; tasks include: - Requirements Analysis - Development of distributed transaction feed procedures, mostly in Python - Implementation of automated result analysis - Design and implementation of test procedures for failover/recovery scenarios in a multi-tier environment - Supervision of regular runs of the automated performance test suite. Target platform will be Linux. Qualifications/Required Skills Python scripting Deep (>3 years) knowledge of Linux, with a focus in the areas - Performance monitoring and tuning - Messaging architectures Performance testing experience, for latency and throughput, incl. data aggregation and reporting Good communications skills Experience of software development in large projects Good overview and knowledge of open source software Ability to work in an international project team. A good command of English is a must. Additional Domain & Business Skills Knowledge of statistical data analysis methods would be an advantage. Experience in mechanisms of interfacing C/C++ and Python would also be advantageous. Frankfurt am Main, Germany Start ASAP to 31.12.09 with good extension prospects for 2010 Rate - Negotiable This is an urgent requirement please contact me or send me your cv as soon as possible. Contact: David Russell - Account manager email: david.russell(a)fdmgroup.com Tel: +49 (0) 69 756 0050 Web: www.fdmgroup.com David Russell Account Manager FDM Group Beethoven Strasse 4, 60325 Frankfurt am Main Germany david.russell(a)fdmgroup.com <mailto:kasia@fdmgroup.com> Tel: + 49 (0) 69 756 0050 Cell: + 49 (0) 173 3592288 Fax: + 49 (0) 69 756 00555 www.fdmgroup.com <http://www.fdmgroup.com/> www.fdmacademy.com <http://www.fdmacademy.com/> BRIGHTON, LONDON, MANCHESTER, LUXEMBOURG, FRANKFURT, ZURICH & NEW YORK This message is from FDM Group Plc, and may contain information that is confidential or privileged. If you are not the intended recipient, please delete the message and any attachments and notify the sender. This email is not intended to create legally binding commitments on behalf of FDM Group Plc, nor do its contents reflect the corporate views or policies of FDM. Any unauthorised disclosure, use or dissemination, either whole or partial, is prohibited. FDM Group Plc is a private limited company registered in England (Reg. No. 2542980). ________________________________________________________________________ This e-mail has been scanned for all viruses by Star Internet. The service is powered by MessageLabs. For more information on a proactive anti-virus service working around the clock, around the globe, visit: http://www.star.net.uk ________________________________________________________________________

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2 Python C++ projects - Financial Industry
by David Russell Feb. 17, 2009

Feb. 17, 2009

Dear Python Group, I have attached two very interesting long term Python projects in the Frankfurt area, Financial industry. I am working exclusively on both requirements, interviews and contracts can be arranged very quickly. If they look interesting to you please feel free to contact me on the contact details below. Thank you for your help, Best Regards David Large Financial Institution - Frankfurt Senior Python C/C++ Developer (f/m) Tasks/Responsibilities Software developer for a complex electronic trading system. The software developer will work in the implementation team of the trading system; tasks include: - Requirements Analysis - Development of a Scripting framework based on Python - Specification - Implementation Target platform will be Linux. Qualifications/Required Skills (Mandatory) Rock Solid Python and C/C++ knowledge Integration of Python with C/C++ libraries Automated Testing Good overview and knowledge of open source software Experience of software development in large projects Good communications skills Ability to work in project teams A good command of English is a must. Additional Domain & Business Skills Knowledge of derivatives trading an advantage, in particular U.S. options. Additional Information: Frankfurt am Main, Germany Start ASAP for a minimum of 6 months Rate - Negotiable This is an urgent requirement please contact me or send me your cv as soon as possible. Contact: David Russell - Account manager email: david.russell(a)fdmgroup.com Tel: +49 (0) 69 756 0050 Web: www.fdmgroup.com //////////////////////////////////////////////////////////////////////// /// Large Financial Institution - Frankfurt am Main Performance / High Availability Test Automation Engineer (f/m) Tasks/Responsibilities Developer of automated test procedures for a high-performance electronic trading system. The engineer will work in the Performance and Technical Test team of the project; tasks include: - Requirements Analysis - Development of distributed transaction feed procedures, mostly in Python - Implementation of automated result analysis - Design and implementation of test procedures for failover/recovery scenarios in a multi-tier environment - Supervision of regular runs of the automated performance test suite. Target platform will be Linux. Qualifications/Required Skills Python scripting Deep (>3 years) knowledge of Linux, with a focus in the areas - Performance monitoring and tuning - Messaging architectures Performance testing experience, for latency and throughput, incl. data aggregation and reporting Good communications skills Experience of software development in large projects Good overview and knowledge of open source software Ability to work in an international project team. A good command of English is a must. Additional Domain & Business Skills Knowledge of statistical data analysis methods would be an advantage. Experience in mechanisms of interfacing C/C++ and Python would also be advantageous. Frankfurt am Main, Germany Start ASAP to 31.12.09 with good extension prospects for 2010 Rate - Negotiable This is an urgent requirement please contact me or send me your cv as soon as possible. Contact: David Russell - Account manager email: david.russell(a)fdmgroup.com Tel: +49 (0) 69 756 0050 Web: www.fdmgroup.com David Russell Account Manager FDM Group Beethoven Strasse 4, 60325 Frankfurt am Main Germany david.russell(a)fdmgroup.com <mailto:kasia@fdmgroup.com> Tel: + 49 (0) 69 756 0050 Cell: + 49 (0) 173 3592288 Fax: + 49 (0) 69 756 00555 www.fdmgroup.com <http://www.fdmgroup.com/> www.fdmacademy.com <http://www.fdmacademy.com/> BRIGHTON, LONDON, MANCHESTER, LUXEMBOURG, FRANKFURT, ZURICH & NEW YORK This message is from FDM Group Plc, and may contain information that is confidential or privileged. If you are not the intended recipient, please delete the message and any attachments and notify the sender. This email is not intended to create legally binding commitments on behalf of FDM Group Plc, nor do its contents reflect the corporate views or policies of FDM. Any unauthorised disclosure, use or dissemination, either whole or partial, is prohibited. FDM Group Plc is a private limited company registered in England (Reg. No. 2542980). ________________________________________________________________________ This e-mail has been scanned for all viruses by Star Internet. The service is powered by MessageLabs. For more information on a proactive anti-virus service working around the clock, around the globe, visit: http://www.star.net.uk ________________________________________________________________________

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