Mailman 3 August 2004 - Cplusplus-sig

Newbie vector_indexing_suite Link Errors
by David Brownell Aug. 18, 2004

Aug. 18, 2004

I just discovered vector_indexing_suite, and am trying to compile the sample application that is linked from the documentation. When I compile the C++ code, I get the following unresolved externals: __declspec(dllimport) void __cdecl boost::python::objects::register_dynamic_id_aux <snip> __declspec(dllimport) void * __cdecl boost::python::objects::find_static_type <snip> __declspec(dllimport) public: __thiscall boost::python::converter::detail::arg_to_python_base::arg_to_python_base <snip> __declspec(dllimport) void * __cdecl boost::python::objects::find_dynamic_type <snip> __declspec(dllimport) class boost::python::api::object const & __cdecl boost::python::objects::identity_function <snip> __declspec(dllimport) struct _object * __cdecl boost::python::objects::make_nurse_and_patient <snip> __declspec(dllimport) void __cdecl boost::python::objects::stop_iteration_error <snip> It seems strange to me that the symbols are decoared with dllimport rather than dllexport, but I didn't see any unusual preprocessor magic going on in the code or described in the documentation that would ensure that these symbols are exported rather than imported. Is there something that I am missing to compile the example? Compiler: Microsoft Visual Studio v7.1 OS: Win XP Boost: linking with $(PYTHON_ROOT)\libs\python23.lib and libboost_python-vc71-mt-gd-1_31.lib (which was compiled using bjam) Python: 2.3 Thanks in advance for your help! David Brownell

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Newbie vector_indexing_suite Link Errors
by David Brownell Aug. 17, 2004

Aug. 17, 2004

I apologize if this is a duplicate post, technical difficulties.... I just discovered vector_indexing_suite, and am trying to compile the sample application that is linked from the documentation. When I compile the C++ code, I get the following unresolved externals: __declspec(dllimport) void __cdecl boost::python::objects::register_dynamic_id_aux <snip> __declspec(dllimport) void * __cdecl boost::python::objects::find_static_type <snip> __declspec(dllimport) public: __thiscall boost::python::converter::detail::arg_to_python_base::arg_to_python_base <snip> __declspec(dllimport) void * __cdecl boost::python::objects::find_dynamic_type <snip> __declspec(dllimport) class boost::python::api::object const & __cdecl boost::python::objects::identity_function <snip> __declspec(dllimport) struct _object * __cdecl boost::python::objects::make_nurse_and_patient <snip> __declspec(dllimport) void __cdecl boost::python::objects::stop_iteration_error <snip> It seems strange to me that the symbols are decoared with dllimport rather than dllexport, but I didn't see any unusual preprocessor magic going on in the code or described in the documentation that would ensure that these symbols are exported rather than imported. Is there something that I am missing to compile the example? Compiler: Microsoft Visual Studio v7.1 OS: Win XP Boost: linking with $(PYTHON_ROOT)\libs\python23.lib and libboost_python-vc71-mt-gd-1_31.lib (which was compiled using bjam) Python: 2.3 Thanks in advance for your help! David Brownell

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RE: [C++-sig] Re: creating an instance of a class_<> object in c+ + and exporting it to python
by Max Khesin Aug. 17, 2004

Aug. 17, 2004

Yep, sorry for disinformation. > > I believe that you will not see the "dummy" method by doing > dir(). IIRC > > boost.python hijacks __getattr__ to delegate the lookup to the c++ > > implemented code. Just try a.dummy(), does it work? > > No it doesn't. The problem is that he used a different name, "A", > for the method. > > -- > Dave Abrahams > Boost Consulting > http://www.boost-consulting.com > > _______________________________________________ > C++-sig mailing list > C++-sig(a)python.org > http://mail.python.org/mailman/listinfo/c++-sig > This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the system manager. This message contains confidential information and is intended only for the individual named. If you are not the named addressee you should not disseminate, distribute or copy this e-mail.

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RE: [C++-sig] Re: creating an instance of a class_<> object in c+ + and exporting it to python
by Max Khesin Aug. 17, 2004

Aug. 17, 2004

I believe that you will not see the "dummy" method by doing dir(). IIRC boost.python hijacks __getattr__ to delegate the lookup to the c++ implemented code. Just try a.dummy(), does it work? max > -----Original Message----- > From: Francois Ostiguy [mailto:ostiguy@fnal.gov] > Sent: Monday, August 16, 2004 5:51 PM > To: c++-sig(a)python.org > Subject: Re: [C++-sig] Re: creating an instance of a class_<> > object in > c++ and exporting it to python > > > > > > > As Mike and I wrote, just do this: > > > > object PythonInstanceOfA = py_get_existing(); > > > > Unfortunately, that does not seem to do quite what I want. > I constructed a simple complete toy example to demonstrate. > > Note the following: > > (1) creating python_object_a forces an undesired instantiation of > a type A (i.e. in addition to the the existing instance a) > > (2) if the interface defines a python object without > an __init__ function, the result is a runtime error: > "Object cannot by created from python." > > (3) if you compile the example, here is what you get when the > module is imported from python > > > Python 2.3.3 (#1, Jul 7 2004, 13:43:38) > [GCC 3.3.3] on linux2 > Type "help", "copyright", "credits" or "license" for more > information. > >>> from inject import * > >>> a > <inject.A object at 0xb733b10c> > >>> dir() > ['A', '__builtins__', '__doc__', '__name__', 'a'] > >>> dir (a) > ['A', '__class__', '__delattr__', '__dict__', '__doc__', > '__getattribute__', '__hash__', '__init__', '__instance_size__', > '__module__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', > '__setattr__', '__str__', '__weakref__'] > >>> > > Note that the object instance "a" has been injected. However, for a > reason that escapes me, the method "dummy" which is > part of the specified interface is not correctly exported. > > Again, my goal is to wrap an existing instance of A, without > having to create a spurious object (basically without having to > call the A constructor more than once). > > Comments, suggestions ??? > > -Francois > > -------------------------------------------------------------- > -------------- > Dr. Jean-Francois OSTIGUY voice: > (630) 840-2231 > Beam Physics Dept MS220 FAX: > (630) 840-6039 > Fermi National Accelerator Laboratory email: > ostiguy(a)fnal.gov > Batavia IL 60510-0500 > WWW:www-ap.fnal.gov/~ostiguy > > > /////// *************** example: inject.cpp **************** ///////// > > #include <boost/python.hpp> > > class A { > public: > A(int d) { _dummy = d; } > int dummy() { return _dummy;} > private: > > int _dummy; > }; > > A* a = 0; > > A* get_existing() { return a; } > > void inject_object(); > > using namespace boost::python; > > class_ <A, A*, boost::noncopyable>* PythonTypeAPtr; > > BOOST_PYTHON_MODULE( inject ) > { > > > static class_ <A, A*, boost::noncopyable> > PythonTypeA("A", init<int>()); > > //*** note: using no_init here will cause a runtime error !! > > PythonTypeA.def("A", &A::dummy); > > /***** this does not seem to export the dummy function to > python. Why ? > > PythonTypeAPtr = &PythonTypeA; > > inject_object(); > > } > > void inject_object() { > > a = new A(99); > > object py_get_existing = > make_function( &get_existing, return_value_policy< > reference_existing_object>() ); > > object python_object_a = (*PythonTypeAPtr)(2); // <<<<<<========== > //****** instantiation of a spurious object > > python_object_a = py_get_existing(); > > > handle<> main_module ( boost::python::borrowed( > PyImport_AddModule("__main__") ) ); > handle<> main_dict ( boost::python::borrowed( > PyModule_GetDict(main_module.get()) )); > PyDict_SetItemString ( main_dict.get(), "a", > python_object_a.ptr() ); > > } > > _______________________________________________ > C++-sig mailing list > C++-sig(a)python.org > http://mail.python.org/mailman/listinfo/c++-sig > This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the system manager. This message contains confidential information and is intended only for the individual named. If you are not the named addressee you should not disseminate, distribute or copy this e-mail.

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ANN: Python/Scientific Job openings at Enthought
by eric jones Aug. 16, 2004

Aug. 16, 2004

Hey Folks, Enthought continues to grow, and we're hiring again. There are several positions open, and most of them involve python+scientific computing. A couple of the positions also involve support of SciPy. I'm very interested in finding a person for the "scientist" job posting that is both able to work well with our customers and also has the personality and interest to work with the SciPy community to help push the library forward. More information is available on our web site. http://www.enthought.com/careers.htm Our current development efforts are in the areas of electromagnetics, geophysics, and graphics (2D and 3D). If you have any questions, please feel free to contact me. Please forward the link to anyone you feel might be interested. thanks, eric

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My latest project
by Neal D. Becker Aug. 16, 2004

Aug. 16, 2004

I'm working on mixing python with c++ algorithms for signal processing applications. I've come to the conclusion that wrapping std::vector is a good choice for containers. I'm pretty happy now with the basic design, and I'd like to share it. This boost-python module wraps (currently) std::vector<double> and std::vector<complex<double>>. It implements (currently) basic arithmetic: vector<T> op vector<T> vector<T> op T vector<T> op complex<T> vector<complex<T>> op vector<complex<T>> vector<complex<T>> op complex<T> vector<complex<T>> op vector<T> vector<complex<T>> op T "in-place" ops not yet implemented.

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Boost Python and Intel C++ 7.1 windows
by Xavier WARIN(Compte LOCAL) - I23 Aug. 16, 2004

Aug. 16, 2004

Hi, While compiling with Intel C++ 7.1 Boost Python , i get this kind of error on class.cpp and a lot of other Boost Python files : C:\boost-1.30.2\boost/type_traits/is_integral.hpp(39): error: class "boost::is_integral<unsigned short>" has already been defined BOOST_TT_AUX_BOOL_TRAIT_CV_SPEC1(is_integral,wchar_t,true) I think that there must be a define that i missed somewhere ! I don't find it Any idea ? Thank you Xavier Warin

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yet another: TypeError: No to_python (by-value) converter found for C++ type:
by tALSit de CoD Aug. 16, 2004

Aug. 16, 2004

Hey guys! I know this has been answered to some extent before, but I just can't get to grips with it, so i know i'm doing something wrong... I export the following: //---------------------------------------------------------------- class_ <cNodeDescriptor, boost::noncopyable> ("cNodeDescriptor", no_init) .def ("getClassId",&cNodeDescriptor::getClassId) .def ("getName",&cNodeDescriptor::getName, return_value_policy <copy_const_reference> ()) ; //---------------------------------------------------------------- class_ <std::vector <cNodeDescriptor *> > ("cNodeDescriptorList") .def ("__iter__", iterator <std::vector <cNodeDescriptor *> > ()) ; And then, in python, i grab a cNodeDescriptorList, and when i try to iterate through it, it spits out: TypeError: No to_python (by-value) converter found for C++ type: class kikura::cNodeDescriptor * So... what am i doing wrong? If more info is needed, i'd be glad to supply it... Cheers!! // talsit.org

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RE: [C++-sig] creating an instance of a class_<> object in c++ an d exporting it to python
by Max Khesin Aug. 13, 2004

Aug. 13, 2004

Maybe I missed something, but I think this should work for you: class_<A, A*, boost::noncopyable> classA("A", noinit);// this is the class object - only one registration! classA.def("f1", &A::f1) .... ; CPPObj cppObj; object instanceOfA1 = classA(&cppObj);// multiple instances object instanceOfA2 = classA(&cppObj); regards, max > -----Original Message----- > From: Francois Ostiguy [mailto:ostiguy@fnal.gov] > Sent: Friday, August 13, 2004 3:23 PM > To: c++-sig(a)python.org > Subject: [C++-sig] creating an instance of a class_<> object > in c++ and > exporting it to python > > > > > Hi - > > I am try in to do the following: > > Consider a C++ class A wrapped using boost.python: > > class_<A, A*, boost::noncopyable>("A", noinit) > .def("f1", &A::f1) > .... > ; > > >From C++, I would like to > > (1) create an instance of a wrapped object "A", initializing it using > a pointer to an existing instance of a C++ A object. > > (2) export the python object into the namespace of an (embedded) > interpreter. > > AFAIK boost.python does not provide a mechanism to accomplish (2), > but that seems straightforward using the Python C-API. > > I am really at a loss on how to achieve (1) using > boost.python. It would > seem like a useful thing to create instances of wrapped objects in > C++. > The most relevant bit of information I found is in the tutorial: > > > > Due to the dynamic nature of Boost.Python objects, any class_<T> may > > also be one of these types! The following code snippet > wraps the class > > (type) > > object. > > > We can use this to create wrapped instances. Example > > object vec345 = ( > > class_<Vec2>("Vec2", init<double, double>()) > > .def_readonly("length", &Point::length) > > .def_readonly("angle", &Point::angle) > > )(3.0, 4.0); > > > > assert(vec345.attr("length") == 5.0); > > > This code does create an instance of vec345; > however, unless I misunderstand something I am under > the impression that every invocation of > class_<A> will re-register the class A. > Perhaps this is not a problem; nevertheless it > appears unnecessarily redundant and potentially error-prone > (multiple class_<A> declarations appearing in different source > files). > > Is it possible to somehow retrieve the class type of an extended > C++ class directly from the interpreter and then > create a new instance ? > > Any comments or insight would be most welcome. > > > -Francois > > -------------------------------------------------------------- > -------------- > Dr. Jean-Francois OSTIGUY voice: > (630) 840-2231 > Beam Physics Dept MS220 FAX: > (630) 840-6039 > Fermi National Accelerator Laboratory email: > ostiguy(a)fnal.gov > Batavia IL 60510-0500 > WWW:www-ap.fnal.gov/~ostiguy > > _______________________________________________ > C++-sig mailing list > C++-sig(a)python.org > http://mail.python.org/mailman/listinfo/c++-sig > This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the system manager. This message contains confidential information and is intended only for the individual named. If you are not the named addressee you should not disseminate, distribute or copy this e-mail.

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creating an instance of a class_<> object in c++ and exporting it to python
by Francois Ostiguy Aug. 13, 2004

Aug. 13, 2004

Hi - I am try in to do the following: Consider a C++ class A wrapped using boost.python: class_<A, A*, boost::noncopyable>("A", noinit) .def("f1", &A::f1) .... ; >From C++, I would like to (1) create an instance of a wrapped object "A", initializing it using a pointer to an existing instance of a C++ A object. (2) export the python object into the namespace of an (embedded) interpreter. AFAIK boost.python does not provide a mechanism to accomplish (2), but that seems straightforward using the Python C-API. I am really at a loss on how to achieve (1) using boost.python. It would seem like a useful thing to create instances of wrapped objects in C++. The most relevant bit of information I found is in the tutorial: > Due to the dynamic nature of Boost.Python objects, any class_<T> may > also be one of these types! The following code snippet wraps the class > (type) > object. > We can use this to create wrapped instances. Example > object vec345 = ( > class_<Vec2>("Vec2", init<double, double>()) > .def_readonly("length", &Point::length) > .def_readonly("angle", &Point::angle) > )(3.0, 4.0); > > assert(vec345.attr("length") == 5.0); This code does create an instance of vec345; however, unless I misunderstand something I am under the impression that every invocation of class_<A> will re-register the class A. Perhaps this is not a problem; nevertheless it appears unnecessarily redundant and potentially error-prone (multiple class_<A> declarations appearing in different source files). Is it possible to somehow retrieve the class type of an extended C++ class directly from the interpreter and then create a new instance ? Any comments or insight would be most welcome. -Francois ---------------------------------------------------------------------------- Dr. Jean-Francois OSTIGUY voice: (630) 840-2231 Beam Physics Dept MS220 FAX: (630) 840-6039 Fermi National Accelerator Laboratory email: ostiguy(a)fnal.gov Batavia IL 60510-0500 WWW:www-ap.fnal.gov/~ostiguy

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