Mailman 3 September 2006 - Cplusplus-sig

Assert fail during deletion for an obj containing external object ptr
by Gangadhar NPK Sept. 19, 2006

Sept. 19, 2006

All, I am a beginner for Boost.Python, so please be kind on the responses. I am trying to create python wrappers for an existing library. I can't change the source of the library ( I don't even have the src to change). Also, since most of the classes are via factories, I can't try to derive from the base classes, so am providing the wrappers by containership. The python wrappers will contain the pointers to the 3rd party libs. When I do this, I am able to get the interface to the third party library's base interface, but during destruction (during the interpretor exit), I get this assert failure: --------------------------- Microsoft Visual C++ Debug Library --------------------------- Debug Assertion Failed! Program: c:\Python24\python.exe File: dbgdel.cpp Line: 51 Expression: _BLOCK_TYPE_IS_VALID(pHead->nBlockUse) For information on how your program can cause an assertion failure, see the Visual C++ documentation on asserts. (Press Retry to debug the application) --------------------------- Abort Retry Ignore --------------------------- I understand that there might be a double delete or invalid deletion that is happening, but I can't point exactly where. The code that generates is attached as a CPP file. This must be something basic that I am missing, but I can't figure out from the boost.python documentation or the wiki. Can someone please point at what I am doing wrong? Thank You Gangadhar P.S:Also, ignore the fact that the 3rd party lib's static function is not exported in the Wrapper class as a member function. That is something that will be changed later.

3 7

implicitly_convertible or order of init's problem
by Roman Yakovenko Sept. 19, 2006

Sept. 19, 2006

Hi. I found some very very strange behaviour. Please, consider next code: struct vector{ vector(){} vector( double ){} vector( const vector& ){} }; struct float_vector{ float_vector(){} float_vector( const float_vector& ){} float_vector( const vector& ){} float_vector( float ){} }; namespace bp = boost::python; BOOST_PYTHON_MODULE( ic_ext ){ bp::class_< float_vector >( "float_vector" ) .def( bp::init< >() ) .def( bp::init< vector const & >() ) .def( bp::init< float >() ) .def( bp::init< const float_vector& >() ); bp::implicitly_convertible< vector const &, float_vector >(); bp::implicitly_convertible< float, float_vector >(); bp::class_< vector >( "vector" ) .def( bp::init< >() ) .def( bp::init< double >() ); bp::implicitly_convertible< double, vector >(); } import ic_ext ic_ext.float_vector( 5.0 ) The last line fails with the error: TypeError: No registered converter was able to extract a C++ reference to type vector from this Python object of type float Question: Why Boost.Python does not use float_vector( float ) constructor? If I reorder the init methods "ic_ext.float_vector( 5.0 )" expression pass: bp::class_< float_vector >( "float_vector" ) .def( bp::init< >() ) .def( bp::init< vector const & >() ) .def( bp::init< const float_vector& >() ) .def( bp::init< float >() ); If I comment out "bp::implicitly_convertible< vector const &, float_vector >();" than "ic_ext.float_vector( 5.0 )" expression pass. It could be nice to understand why this happens. I attached small example that reproduce the problem.( I hope this time I did it right :-) ) Thanks. -- Roman Yakovenko C++ Python language binding http://www.language-binding.net/

2 2

how to pass list to my c++ function which need an argument of array
by Qinfeng(Javen) Shi Sept. 19, 2006

Sept. 19, 2006

Dear all, I wrapped a c++ function into python by pyste. It is like: func1(double[] a); main() { double a[]={1,2,3}; func1(a); } I can run main in python. But I what directly call func1 in python as well. Python doesn't have a type called double[], but list(or numarray) has the similar property to double[]. So if I can pass list to func1, it will be fine. Does anybody know how can I pass list to func1 in python? Any suggestion is appreciated. Javen. Research School of Information Sciences and Engineering Australian National University Locked Bag 8001 Canberra ACT 2601

2 1

Returning a Python object to C++ (is get_owner the right way?)
by Jack Lloyd Sept. 18, 2006

Sept. 18, 2006

I have a scenario where I'm wrapping a virtual base class that offers cloning (here, sending a clone message to an object means "return a newly constructed object of whatever type you are"), and want to inherit from that type in Python. Simply implementing that function in Python (eg: class MySubclass(mylib.MyBaseClass): def clone(self): return MySubclass() led to "returning a dangling reference" errors, so I'm using the technique Dave suggested in http://mail.python.org/pipermail/c++-sig/2004-December/008379.html (basically, use get_owner, get ahold of the __class__ attribute, and call the constructor, then keep a reference to the copy-constructed Python object around so it is not destroyed until the lifetime of the C++ object is over, all held inside another class that simply forwards the appropriate messages to the Python object). This has been working fine for me, however since get_owner is still undocumented (AFAICT; couldn't find it anywhere in the 1.33.1 docs), and generally the technique led to some rather ugly code, I wanted to check and see if any new technique/method for dealing with this situation had developed since that discussion? I hope I've managed to explain what I'm doing clearly; if not, I'd be happy to post a minimal example of my method. Thanks, Jack

2 2

Problems Compiling Boost.Python w/ Indexing Suite v2
by Lakin Wecker Sept. 18, 2006

Sept. 18, 2006

Hi all, I've been having problems getting boost.python from CVS with the v2 indexing suite. I used the instructions from here: http://www.boost.org/more/getting_started.html#CVS To get boost.python from cvs. Then I used the instructions from here: http://mail.python.org/pipermail/c++-sig/2003-October/005802.html to switch to v2 of the indexing suite. Finally, I used http://www.boost.org/libs/python/doc/building.html as instructions to build boost.python. Specifically, I executed "bjam -sTOOLS=gcc test" from the libs/python/test directory. The following is the log of the output from the above build command: http://lakin.weckers.net/v2_log.txt I'm running Ubuntu 6.06, which has g++ (GCC) 4.0.3 (Ubuntu 4.0.3-1ubuntu5) Thanks in advance, Lakin

3 2

What if a Python override returns several values?
by Matthias Baas Sept. 18, 2006

Sept. 18, 2006

Hi, how can I obtain the result tuple from calling a Python override that returns several values? The following example is from the tutorial and works fine as long as the Python implementation of f returns an integer. struct BaseWrap : Base, wrapper<Base> { int f() { return this->get_override("f")(); } }; But if I have another virtual member function "void g(int& a, int &b)" which returns two integers, then I'd like the Python version to take no arguments and return a tuple (a,b). But how does the wrapper look like in this case? I would have expected something like: void g(int& a, int& b) { boost::python::tuple tup = this->get_override("g")(); a = ...extract an int from tup[0]... b = ...extract an int from tup[1]... } But when I run this code I get the following error at runtime: TypeError: No registered converter was able to extract a C++ reference to type boost::python::tuple from this Python object of type tuple So how is this dealt with using the "wrapper" class? (This is Boost.Python v1.33.1 on Linux) - Matthias -

3 11

Fwd: Problems Compiling Boost.Python w/ Indexing Suite v2
by Lakin Wecker Sept. 18, 2006

Sept. 18, 2006

Posting this back to the c++-sig mailing list, where it belongs. :) Lakin ---------- Forwarded message ---------- From: Lakin Wecker <lakin.wecker(a)gmail.com> Date: Sep 18, 2006 10:30 AM Subject: Re: Problems Compiling Boost.Python w/ Indexing Suite v2 To: python-ogre-developers(a)googlegroups.com I assume you meant boost/python/operators.hpp ... as that is the only file where I could find that line. I commented it out, did a bjam clean, and then rebuilt using the same command. Still no luck, but different problems this time: http://lakin.weckers.net/v2_log.2.txt At this point, I haven't had time to look into the problem, so I hope it isn't something simple. Lakin On 9/17/06, Roman Yakovenko <roman.yakovenko(a)gmail.com> wrote: > > On 9/17/06, Lakin Wecker <lakin.wecker(a)gmail.com> wrote: > > > > Hi all, > > > > I've been having problems getting boost.python from CVS with the v2 > > indexing suite. I used the instructions from here: > > http://www.boost.org/more/getting_started.html#CVS To get boost.python > > from cvs. Then I used the instructions from here: > > http://mail.python.org/pipermail/c++-sig/2003-October/005802.html to > > switch to v2 of the indexing suite. Finally, I used > > http://www.boost.org/libs/python/doc/building.html as instructions to > > build boost.python. Specifically, I executed "bjam -sTOOLS=gcc test" > > from the libs/python/test directory. > > > > The following is the log of the output from the above build command: > > http://lakin.weckers.net/v2_log.txt > > > > I'm running Ubuntu 6.06, which has g++ (GCC) 4.0.3 (Ubuntu 4.0.3-1ubuntu5) > > > > It has nothing to do with indexing suite v2. Just comment > BOOST_PYTHON_UNARY_OPERATOR(repr, lexical_cast<std::string>, repr) > line in operators.hpp in you will be okey. I found this yesterday too. > > > Thanks in advance, > > > > Lakin > > > -- > Roman Yakovenko > C++ Python language binding > http://www.language-binding.net/ > > --~--~---------~--~----~------------~-------~--~----~ > You received this message because you are subscribed to the Google Groups "Python Ogre Developers" group. > To post to this group, send email to python-ogre-developers(a)googlegroups.com > To unsubscribe from this group, send email to python-ogre-developers-unsubscribe(a)googlegroups.com > For more options, visit this group at http://groups.google.com/group/python-ogre-developers > -~----------~----~----~----~------~----~------~--~--- > >

1 0

range and iterator
by CT Sept. 18, 2006

Sept. 18, 2006

Hi , Does someone can give me some help on how to expose correctly an array of pointers using boost.python ? here is a small example of my code i have a class class A { public: A(std::string &oName); ~A(){} const std::string &GetName() const; } class B { std::vector<*A> *poNames public: std::vector<*A> GetNames() { return *poNames } } assume that there is two instances of A in the container of the object B now for the boost::python code. I would like to be able to expose class a and class b and the vector of A* typedef std::vector<A*> array_proj; array_proj::iterator begin_array_proj(array_proj &x) {return x.begin();} array_proj::iterator end_array_proj(array_proj &x) {return x.end();} BOOST_PYTHON_MODULE(pysession) { class_<A>("object a",init<std::string &) .def("GetName",&A::GetName,return_value_policy <copy_const_reference>() ) ; class_<B>("object B") .def("GetNames", &B::GetNames, return_value_policy<manage_new_object>() ) ; class_<std::vector<*A> >("array of pointer to objects A") .def("__iter__", range( begin_array_proj, end_array_proj) ) ; } Now in python for example I call #create a new object B #and iterate over all of the object A #assume that there are two object of type A in the vector oNewSession = pysession.B() oVector = oNewSession.GetNames() for oA in oVector.__iter__(): print (oA.GetName()) i have this error when i start the python script for oA in oVector.__iter__(): TypeError: No to_python (by-value) converter found for C++ type: class ::A * Does someone can give me some help on how to expose correctly an array of pointers using boost.python ?

1 0

how to use PyRun_SimpleFile in a multithread C++ program?
by jack833 Sept. 18, 2006

Sept. 18, 2006

Hi,Every one, i need help about PyRun_simplefile function,the program i'm writing is a C++ program which will start serveral threads .each thread will use PyRun_simplefile function to do something,but python script file is the same. now the program is offten crash down,but there is no problem while only thread which use PyRun_simplefile,but that is not what i wanted. is there anyone who can tell me how to resove it. -- View this message in context: http://www.nabble.com/how-to-use-PyRun_SimpleFile-in-a--multithread-C%2B%2B… Sent from the Python - c++-sig mailing list archive at Nabble.com.

2 1

how to pass function pointer to a constructor of a template class when wrap it by pyste
by Qinfeng(Javen) Shi Sept. 14, 2006

Sept. 14, 2006

Dear all, I have a class (in hello.cc file) whose constructor assgins a value to a global function pointer. It is compiled by gcc and it works well. But it always reports an error when I used bjam to build the hello.cpp file (which is produced by pyste). If I remove the template, it works. But I do need the template. Does anybody know how to wrap it correctly? Any suggestion is appreciated. The hello.cc, hello.pyste, Jamfile are as following: /********************hello.cc*************/ #include <stdio.h> float add(float a, float b) { return a+b; } float minus(float a, float b) { return a-b; } float (*op)(float a, float b) = add; template<class P> class cover_tree { P value; public: cover_tree(float (* metric)(float a, float b)) { op= metric; } cover_tree() { } }; int main() { float a,b,c; a = 1; b = 2; cover_tree<float> ct2(minus); c = op(a,b); printf("%f\n",c); } /************************hello.pyste*********/ cover_tree = Template('cover_tree','hello.cc') cover = cover_tree("float") Function("main", "hello.cc") /************************Jamfile***********/ # This is the top of our own project tree project-root ; # Include definitions needed for Python modules import python ; extension hello # Declare a Python extension called hello : hello.cpp # requirements and dependencies for Boost.Python extensions <template>@boost/libs/python/build/extension ; -- Javen Research School of Information Sciences and Engineering Australian National University Locked Bag 8001 Canberra ACT 2601

1 0