Mailman 3 January 2004 - Cplusplus-sig

pyste && private copy constructor question.
by Hanz Meizer Jan. 31, 2004

Jan. 31, 2004

Hi, I'm trying to make the classes of an existing c++-project accessible to python via the means of python. Unfortunately, there is a class that has an interface like this: ... protected: Bla(const std::string&, int); private: Bla(); Bla(const Element&); ... I get the following error: .. Bla.h:94: ` Blub::Bla(const Blub::Bla&)' is private ... My question is: How can I modify my pyste input file to work around this problem? I figure that it's related to the fact that the copy constructor is private. Unfortunately, I can't find any reasonable pyste tutorial that covers more sophisticated topics and examples. Any help, links, pointers etc. welcome. --tt. P.S.: Unfortunately, modifying the C++ Headers is not an option :-|

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replacing object constructors by factories
by Stefan Seefeld Jan. 31, 2004

Jan. 31, 2004

hi there, I'm exposing classes to python which are not directly instantiable via constructors, but via factories. However, I'd like to be able to instantiate class 'Foo' by foo = Foo() nonetheless, I'v managed to do that by defining 'Foo' as a global Function returning a 'Foo' instance. But as soon as that is done, python obviously reports 'Foo' as a function, not a 'class'. Are there other ways provide 'user hooks' as constructors ? Thanks, Stefan

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More std::vector, this time with pyste
by Neal D. Becker Jan. 30, 2004

Jan. 30, 2004

I'm trying out pyste to see whether it is useful for exporting std::vector. I get an error, which I don't know how to resolve. Test2.pyste---------------------- P = Template ("std::vector", "Test2.H") exclude (P.at) exclude (P.front) exclude (P.back) exclude (P.assign) P("double") Test2.H------------------ #include <vector> /usr/bin/pyste.py --module=Test2 Test2.pyste Module Test2 generated 1.94 seconds g++ -shared -I /usr/include/python2.3 -I /usr/local/src/boost_1_31_0_rc2 -I ./ -L /usr/local/src/boost_1_31_0_rc2/stage/lib/ -lboost_python-gcc Test2.cpp -Wl,-rpath -Wl,/usr/local/src/boost_1_31_0_rc2/stage/lib -lfftw -o Test2.so In file included from /usr/include/python2.3/Python.h:8, from /usr/local/src/boost_1_31_0_rc2/boost/python/detail/wrap_python.hpp:121, from /usr/local/src/boost_1_31_0_rc2/boost/python/detail/prefix.hpp:13, from /usr/local/src/boost_1_31_0_rc2/boost/python/args.hpp:9, from /usr/local/src/boost_1_31_0_rc2/boost/python.hpp:12, from Test2.cpp:3: /usr/include/python2.3/pyconfig.h:847:1: warning: "_POSIX_C_SOURCE" redefined In file included from /usr/include/limits.h:26, from /usr/lib/gcc-lib/i386-redhat-linux/3.3.2/include/limits.h:122, from /usr/lib/gcc-lib/i386-redhat-linux/3.3.2/include/syslimits.h:7, from /usr/lib/gcc-lib/i386-redhat-linux/3.3.2/include/limits.h:11, from /usr/local/src/boost_1_31_0_rc2/boost/python/detail/wrap_python.hpp:27, from /usr/local/src/boost_1_31_0_rc2/boost/python/detail/prefix.hpp:13, from /usr/local/src/boost_1_31_0_rc2/boost/python/args.hpp:9, from /usr/local/src/boost_1_31_0_rc2/boost/python.hpp:12, from Test2.cpp:3: /usr/include/features.h:131:1: warning: this is the location of the previous definition /usr/local/src/boost_1_31_0_rc2/boost/python/object/inheritance.hpp: In static member function `static void* boost::python::objects::implicit_cast_generator<Source, Target>::execute(void*) [with Source = std::vector<double, std::allocator<double> >, Target = std::_Vector_alloc_base<double, std::allocator<double>, true>]': /usr/local/src/boost_1_31_0_rc2/boost/python/object/inheritance.hpp:123: instantiated from `void boost::python::objects::register_conversion(bool, Source*, Target*) [with Source = std::vector<double, std::allocator<double> >, Target = std::_Vector_alloc_base<double, std::allocator<double>, true>]' /usr/local/src/boost_1_31_0_rc2/boost/python/object/class_converters.hpp:61: instantiated from `void boost::python::objects::register_base_of<Derived>::operator()(Base*) const [with Base = std::_Vector_alloc_base<double, std::allocator<double>, true>, Derived = std::vector<double, std::allocator<double> >]' /usr/local/src/boost_1_31_0_rc2/boost/mpl/for_each.hpp:76: instantiated from `static void boost::mpl::aux::for_each_impl<false>::execute(Iterator*, LastIterator*, TransformFunc*, F) [with Iterator = boost::mpl::vector_iterator<boost::mpl::vector1<std::_Vector_alloc_base<double, std::allocator<double>, true> >, boost::mpl::integral_c<long int, 0> >, LastIterator = boost::mpl::vector_iterator<boost::mpl::vector1<std::_Vector_alloc_base<double, std::allocator<double>, true> >, boost::mpl::integral_c<long int, 1> >, TransformFunc = boost::mpl::protect<boost::mpl::bind1<boost::mpl::quote1<boost::add_pointer, boost::mpl::void_>, boost::mpl::arg<-1> > >, F = boost::python::objects::register_base_of<std::vector<double, std::allocator<double> > >]' /usr/local/src/boost_1_31_0_rc2/boost/mpl/for_each.hpp:100: instantiated from `void boost::mpl::for_each(F, Sequence*, TransformOp*) [with Sequence = boost::python::bases<std::_Vector_alloc_base<double, std::allocator<double>, true>, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_>, TransformOp = boost::add_pointer<boost::mpl::_>, F = boost::python::objects::register_base_of<std::vector<double, std::allocator<double> > >]' /usr/local/src/boost_1_31_0_rc2/boost/python/object/class_converters.hpp:88: instantiated from `void boost::python::objects::register_class_from_python(Derived*, Bases*) [with Derived = std::vector<double, std::allocator<double> >, Bases = boost::python::bases<std::_Vector_alloc_base<double, std::allocator<double>, true>, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_>]' /usr/local/src/boost_1_31_0_rc2/boost/python/class.hpp:626: instantiated from `void boost::python::class_<T, X1, X2, X3>::register_() const [with T = std::vector<double, std::allocator<double> >, X1 = boost::python::bases<std::_Vector_alloc_base<double, std::allocator<double>, true>, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_>, X2 = boost::python::detail::not_specified, X3 = boost::python::detail::not_specified]' /usr/local/src/boost_1_31_0_rc2/boost/python/class.hpp:640: instantiated from `void boost::python::class_<T, X1, X2, X3>::register_holder() [with T = std::vector<double, std::allocator<double> >, X1 = boost::python::bases<std::_Vector_alloc_base<double, std::allocator<double>, true>, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_>, X2 = boost::python::detail::not_specified, X3 = boost::python::detail::not_specified]' /usr/local/src/boost_1_31_0_rc2/boost/python/class.hpp:275: instantiated from `boost::python::class_<T, X1, X2, X3>::class_(const char*, const boost::python::init_base<DerivedT>&) [with DerivedT = boost::python::init<boost::python::optional<const std::allocator<double>&, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_>, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_>, T = std::vector<double, std::allocator<double> >, X1 = boost::python::bases<std::_Vector_alloc_base<double, std::allocator<double>, true>, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_, boost::mpl::void_>, X2 = boost::python::detail::not_specified, X3 = boost::python::detail::not_specified]' Test2.cpp:15: instantiated from here /usr/local/src/boost_1_31_0_rc2/boost/python/object/inheritance.hpp:100: error: ` std::_Vector_alloc_base<double, std::allocator<double>, true>' is an inaccessible base of `std::vector<double, std::allocator<double> >' I guess I need to convince pyste not to put std::_Vector_alloc_base<double, std::allocator<double>, true> in bases? No idea how.

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call python method from C++
by Fabrizio Jan. 30, 2004

Jan. 30, 2004

sorry for my english i want to call python method in my C++ code D:\test\boost_python\Release>python test.py Traceback (most recent call last): File "test.py", line 27, in ? eriser.Update(a) TypeError: Update() takes exactly 2 arguments (1 given) C++ code class IRenderable { public: virtual ~IRenderable() {} virtual void Init() {} virtual void Render() {} virtual void Update(float dt) {} }; class IRenderableWrapper : public IRenderable { public: PyObject* self; IRenderableWrapper(PyObject* self_) : self(self_) {} void Init() { return boost::python::call_method<void>(self, "Init"); } void DefaultInit() { return IRenderable::Init(); } void Render() { return boost::python::call_method<void>(self, "Render"); } void DefaultRender() { return IRenderable::Render(); } void Update(float dt) { return boost::python::call_method<void>(self, "Update"); } void DefaultUpdate(float dt) { return IRenderable::Update(dt); } }; void CallUpdate(IRenderable& i) { i.Update(2.3f); } BOOST_PYTHON_MODULE(eriser) { class_<IRenderable, IRenderableWrapper, boost::noncopyable>("IRenderable") .def("Init", &IRenderable::Init, &IRenderableWrapper::DefaultInit) .def("Update", &IRenderable::Update, &IRenderableWrapper::DefaultUpdate) .def("Render", &IRenderable::Render, &IRenderableWrapper::DefaultRender) ; def("Update", CallUpdate); } python script class Scene(eriser.IRenderable): def Init(self): print "pass"; def Update(self, dt): print dt a = Scene() eriser.Update(a) Thanks in advance. fabrizio --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.573 / Virus Database: 363 - Release Date: 28/01/2004

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Problems with link stage... (Number 2)
by Jeff Holle Jan. 30, 2004

Jan. 30, 2004

trying to build a cpp test client of my python extension shared library, which uses boost.python. I'm using linux with gcc v3.3, python v2.3.2, boost 04/01/26 CVS head. I've successfully built a boost.python extension module and tested it with python. Now I'm stuck at the link stage of an equivalent C++ client. The problem is my link is failing with "unresolved references" like: PySequence_DelSlice' PyNumber_InPlaceXor' PyNumber_Subtract' PyMem_Malloc' PyComplex_RealAsDouble' PyModule_Type' PySequence_DelSlice' PyNumber_InPlaceXor' They mostly emulate from the boost_python library. In investigating what Python 2.3.2 gives to my linux system, I've only found that the likely cantigate is libpython2.3.a. Including this library to my bjam file appears to have no affect. My current Jamfile is: subproject cppTest ; import python ; exe cppTest : # sources cppTest.cpp : # requirements <lib>../../../Python-2.3.2/libpython2.3.a <include>/usr/local/include/python2.3 <find-library>UMLModel <library-path>. : release ; A more general question: My experience with linux and gcc is much more limited to my windows programming background. In windows, problems like this where the client of a dll gains an appetite for resources used only by the dll points to a problem of the client code using something other than an abstract interface from the dll. I have modified my shared library to only use abstract interfaces. Note this involves a simple class factory. This procedure has not altered the linking problems that I have. Does linux share this problem with windows, MSVC 6.0 sp5? Second part: I've got more information about my problem via experimentation. First, I cleaned up my Jamfile to: subproject cppTest ; import python ; exe cppTest : # sources cppTest.cpp : # requirements <find-library>python2.3 <find-library>UMLModel <library-path>. : release ; In doing "bjam -a -n", I can see that both "-lpython2.3" and "-lUMLModel" are properly feed to the linker. I get the same 130 link errors has above with python2.3, but when I try python2.2 it is reduced to a single link error, concerning "PyCFunction_NewEx". Info found on the web about this is that it was changed from a function to a macro at some time in the past. Also, I installed python 2.3.3 and rebuilt everything. Nothing changed. Last, I find that both python 2.3.2 and python 2.3.3 builds did not produce a shared library equivalent to libpython2.3.a. Maybe this is a problem?

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pyste and C++ namespaces
by Jeff Holle Jan. 30, 2004

Jan. 30, 2004

In further pyste experimenting, I put my C++ code in a namespace. First surprise was that I needed to decorate my class name in the *.pyste file with its housed namespace. Doing this allowed pyste to run successfully, but. Second surprise that the generated python interface class now contains a "wrapper" class. Is this necessary? The class is easily accessible by opening the namespace, or not, depending on the C++ choice.

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Problems with link stage...
by Jeff Holle Jan. 29, 2004

Jan. 29, 2004

trying to build a cpp test client of my python extension shared library, which uses boost.python. I'm using linux with gcc v3.3, python v2.3.2, boost 04/01/26 CVS head. I've successfully built a boost.python extension module and tested it with python. Now I'm stuck at the link stage of an equivalent C++ client. The problem is my link is failing with "unresolved references" like: PySequence_DelSlice' PyNumber_InPlaceXor' PyNumber_Subtract' PyMem_Malloc' PyComplex_RealAsDouble' PyModule_Type' PySequence_DelSlice' PyNumber_InPlaceXor' They mostly emulate from the boost_python library. In investigating what Python 2.3.2 gives to my linux system, I've only found that the likely cantigate is libpython2.3.a. Including this library to my bjam file appears to have no affect. My current Jamfile is: subproject cppTest ; import python ; exe cppTest : # sources cppTest.cpp : # requirements <lib>../../../Python-2.3.2/libpython2.3.a <include>/usr/local/include/python2.3 <find-library>UMLModel <library-path>. : release ; Could somebody tell me what I need to do to resolve this problem? A more general question: My experience with linux and gcc is much more limited to my windows programming background. In windows, problems like this where the client of a dll gains an appetite for resources used only by the dll points to a problem of the client code using something other than an abstract interface from the dll. I have modified my shared library to only use abstract interfaces. Note this involves a simple class factory. This procedure has not altered the linking problems that I have. Does linux share this problem with windows, MSVC 6.0 sp5?

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Catching C++ exceptions in Python
by James Gunn Jan. 28, 2004

Jan. 28, 2004

*** Before acting on this e-mail or opening any attachment you are advised to read the disclaimer at the end of this e-mail *** Hi, I've been trying to figure out how I can catch my C++ exceptions in Python. I started looking at the register_exception_translator template but this does not see to do what I need. Basically if I have a C++ function such as the following: void OpenFile( std::string const& fileName) and this throws one of my C++ exceptions (such as FileException) how can I catch the FileException in python. I have wrapped the OpenFile function with the following: void Translate( FileException const& e ) { PyErr_SetString( PyExc_UserWarning, e.what() ); } BOOST_PYTHON_MODULE(testmod) { register_exception_translator<FileException>(&Translate); def("openFile", &OpenFile); } All I can get with this is the exception error message. I really need to be able to do something like the following in Python: import testmod try: testmod.openFile("non-existent file") except testmod.FileException: # do something here with exception I am really stuck as to how I can achieve this. Any help or advice will be appreciated. Thanks in advance. James Gunn Software Developer Communisis Chorleys Ltd Computer Bureau Manston Lane Crossgates Leeds LS15 8AH Tel: 0113 305 3001 Email: James.Gunn(a)communisis-dm.co.uk ********************************************************************** Please note: This e-mail and its attachments contain only the opinions of the sender and do not necessarily reflect the policy(s) of the communisis group in general. Employees of the communisis group are required not to make any defamatory statements and not to infringe or authorise any infringement of copyright or any other legal right by e-mail. Any such communication is therefore outside the scope of employment of the individual concerned. The communisis group will not accept any liability in respect of such a communication. Confidentiality: This e-mail and any attachments, together with their contents, are confidential unless otherwise explicitly stated in writing by the sender of this e-mail and are for the intended recipient only. If they have come to you in error you must not take any action in respect of them, which includes but is not limited to reproducing, sending or storing them, other than to notifying the sender immediately of the mistake, and deleting the e-mail, any attachments and any reproductions made by replying to it. Viruses: This e-mail and any attachments have been scanned for viruses but we cannot guarantee that they are virus free. The recipient should check this e-mail and any attachments for viruses. The communisis group accepts no responsibility for any damage caused by any virus transmitted by this e-mail or any of its attachments. In the event of any unauthorised copying or forwarding, the recipient will be required to indemnify the communisis group against any claim for loss or damage caused by any viruses or otherwise. ********************************************************************** ________________________________________________________________________ This email has been scanned for all viruses by the MessageLabs Email Security System. For more information on a proactive email security service working around the clock, around the globe, visit http://www.messagelabs.com ________________________________________________________________________

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class callback
by Leo Yee Jan. 28, 2004

Jan. 28, 2004

Hi, I am coding c++ object which gives callback functions to python. I encountered these problem that a c++ object destruction method won't be called if a python class holds the c++ object that has a callback function of this python class. Let's look the code. using namespace boost::python; struct cHolder { cHolder() {} ~cHolder() { // we can't reach here } void SetCallback( const object &o ) { m_o = o; } void OnCallback(void) { if( m_o ) m_o(); } object m_o; }; BOOST_PYTHON_MODULE( hello ) { class_< cHolder >( "cHolder" ) .def( "SetCallback", cHolder::SetCallback ) .def( "OnCallback", cHolder::OnCallback ); } The python code looks like this: from hello import * class cA: def __init__(self): self._holder = cHolder() self._holder.SetCallback( self.callback ) def callback( self ) : print 'callback' a = cA() a._holder.OnCallback() I also tried to manuaully use python weakref functions to help me solving this problem but I found that the weak reference released just as I called the 'setcallback' function. The weak reference code looked like this: struct cHolder { cHolder() { m_weakRef = NULL; } ~cHolder() { Py_XDECREF( m_weakRef ); } void SetCallback( const object &o, const object &free ) { m_weakRef = PyWeakref_NewRef( o.ptr(), free.ptr() ); // the pyobject was just freed as this function had been finished } void OnCallback(void) { if( m_weakRef ) { object o(borrowed(PyWeakref_GetObject( m_weakRef ))); if( o ) o(); // We can't reach here because o is always None } } PyObject *m_weakRef; }; Does anybody know how I can solve this problem? Thanks in advance. Leo Yee

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Re: will pyste support Class Properties?
by Jeff Holle Jan. 27, 2004

Jan. 27, 2004

I see that this feature of boost.python is supportable via the module_code directive of pyste. This is the one major boost.python feature that find missing from pyste version 0.9.28. Will it support it in the future? Or does it now and it just isn't documented?

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