Mailman 3 October 2006 - Cplusplus-sig

Base class defined in other header file not included in bp::bases<>
by Haridev, Meghana Sept. 14, 2008

Sept. 14, 2008

Hi Folks, I'm having some trouble generating boost-python wrapper code using pyplusplus for a derived class which has one of its base classes defined in another file. Simple scenario: mydir/ other.hpp: class baseB{ }; hierarchy.hpp: #include "other.hpp" class baseA{ }; class derivedC: public baseA, public baseB{ }; generate_code.py: import os from pyplusplus import module_builder mb = module_builder.module_builder_t( files=['hierarchy.hpp'] ) mb.build_code_creator( module_name='inherit' ) mb.code_creator.user_defined_directories.append( os.path.abspath('.') ) mb.write_module('boost_hierarchy.cpp') ------------------------------------------------------------------------ ------------------------------------------------- Generated code (boost_hierarchy.cpp) looks like this: // This file has been generated by pyplusplus. #include "boost/python.hpp" #include "hierarchy.hpp" namespace bp = boost::python; BOOST_PYTHON_MODULE(inherit){ bp::class_< baseA >( "baseA" ); bp::class_< derivedC, bp::bases< baseA > >( "derivedC" ); } How can I get pyplusplus to add 'baseB' to bp::bases<> for 'derivedC' class when 'baseB' class is defined in another file (present in the same directory or different directory)? When I move the definition of 'baseB' class to hierarchy.hpp, boost wrapper for 'derivedC' is correctly generated as: bp::class_< derivedC, bp::bases< baseA, baseB > >( "derivedC" ); Thanks, -Meghana.

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'iteritems', 'iterkeys' and 'itervalues' in dict
by Nindi Singh April 11, 2008

April 11, 2008

Apolgies for not putting the subject line in my last email. In the Boost.Python dict class there are methods 'iteritems', 'iterkeys' and 'itervalues' all returning objects. How exactly are you supposed to use these objects (iterators) ? ___________________________________________________________ Inbox full of spam? Get leading spam protection and 1GB storage with All New Yahoo! Mail. http://uk.docs.yahoo.com/nowyoucan.html

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C++ singleton
by Emmanuel Taurel Oct. 31, 2007

Oct. 31, 2007

Hello everybody, I am actually writing an interface to python for an existing C++ library using Boost. This library has a C++ singleton class. This class has only one constructor (with arguments) which is "protected" because it's a singleton. I am not able to build a Boost interface to this class because the compiler complains that the constructor I have given to Boost in the class_xxx constructor argument is not public (which is true) ! Therefore, my question is simple : How is it possible to interface such a class with only one constructor which is protected and a static method to create/access the object ? Thank's very much for your answer. Sincerely Emmanuel Taurel (etaurel(a)cells.es) PS : By the way, is there a searchable archive of this mailing list ?

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a question about embedding python in c++
by David Toneian Oct. 31, 2006

Oct. 31, 2006

hi, i would like to embed a scripting language in my (planned) c++ apps. i've found boost.python now, and it seems to be what i need. nevertheless, i'm still unsure whether i can do the follwoing with boost.python: (note that the python-related part is just pseudo-code, of course :> ) class someNumber { public: float x; someNumber() : x(0) {} }; class myClass { public: int a; someNumber* number; myClass() : a(0) {number=new someNumber();} ~myClass(){delete number;} void add(const int x) {a+=x;} }; void printHelloPython() { std::cout<<"hello python"; } int main() { myClass foobar(); revealFunctionToPython(&printHelloPython); revealClassToPython("someNumber"); revealClassToPython("myClass"); revealInstanceToPython(&foobar); runThatPythonScrip(); return foobar.a+foobar.number.x; } Where the python code sets a to 5 directly (something like foobar.a=5), calls printHelloPython(), sets the someNumber instance inside foobar to 1330 and then calls foobar.add(2). I'd expect an output of "hello python" and the returned result from main to be 1337. so, can i manipulate the c++ instance from within a python script? if i can't, is there a scripting language that i can embed in my application that is able to do the job? thank you, david

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Re: [C++-sig] ERROR:illegal hardware instruction on MAC OS when using import_array()
by Nat Goodspeed Oct. 30, 2006

Oct. 30, 2006

________________________________________ > From: c++-sig-bounces(a)python.org > [mailto:c++-sig-bounces@python.org] On Behalf Of Qinfeng(Javen) Shi > Sent: Friday, October 27, 2006 2:25 AM > To: c++-sig(a)python.org > Cc: Kishor Gawande > Subject: [C++-sig] ERROR:illegal hardware instruction on MAC OS > when using import_array() > > I wrapped a c++ code which can receive numpy.array data in python > on linux. For that I used import_array() in c extension. It works > well on linux. Then I bjam it in MAC OS without any error. But > when I import it in python on MAC OS, it reports a error. It > seems that import_array() evoked the error. [Nat] I haven't used numpy, and this is not a problem with which I'm familiar. Just contributing a thought. Have you tried using py2app to build your extension on OS X? http://svn.pythonmac.org/py2app/py2app/trunk/doc/index.html I've used py2app, though I've never used its compilation feature: we've always built our extensions using Xcode. But it does claim to build C++ Python extensions using the right set of build options to allow Mac Python to import them.

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[boost::python] Unresolved overloaded function - methods with same name
by yardbird Oct. 30, 2006

Oct. 30, 2006

Hello, I have a problem with getters/setters methods with the same name which both return cont/non-const reference to a class' data member. For instance: struct Foo { Foo(int x) { b = x; } int const& get_b() const { return b; } int & get_b() { return b; } private: int b; }; // Wrapper code BOOST_PYTHON_MODULE(my_module) { class_<Foo>("Foo", init<int>()) .def("get_b", &Foo::get_b); } When I try to build this it seems like it cannot decide whether it should use the const or non-const method to access the member. The error I get is something like: [...]no matching function for call to [...] ::def(const char [6], <unresolved overloaded function type>,[...] I know I could just make "b" public and then use .defreadonly/.defreadwrite to access it, but I would like to keep unaltered the original layout of the class. Sorry if this is a stupid question, I looked at the documentation and tried to use "return_internal_reference<>()" and the likes but I really could not figure it out. Thanks very much, Francesco

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pointer_holder and pure virtual base classes
by Allen Bierbaum Oct. 29, 2006

Oct. 29, 2006

This is a followup to my efforts in the thread here: http://thread.gmane.org/gmane.comp.python.c++/10125/focus=10125 I seemed to have everything working but I just ran into a new problem. A simplified summary is: class Base { public: int getSomething() = 0; }; class DerivedA : public Base { public: int getSomething() { return 1; } } class DerivedB : public DerivedA { public: int getSomething() { return 1; } } I am wrapping these classes with a held_type of RefPtr<classType> except for the Base class because it is pure virtual. (this is a custom ref counting pointer; see thread above for details) I thought everything was good until I tried to wrap a factory class. The class can return any class type but it returns it through a pointer to the Base class like this: class Store { public: RefPtr<Base> getObject(int id); }; The problem wrapping this is that since I do not have a held_type registered for the base type as RefPtr<Base>, there is no to_python (by-value) converter found for C++ type: RefPtr<Base>. As an attempt to fix this I set the held type for Base to RefPtr<Base>, but this fails because pointer_holder.hpp line 179 needs to be able to alloate an object of the pointee type. Since it is pure virtual the compiler fails here. So my question is, when dealing with a polymorphic hierarchy like this is is possible to use a smart pointer as a held type for the most basic types? (ie. the pure virtual base). If not, does anyone have suggested workarounds for me to try? Thanks, Allen Note: One simplification I made above is that there is another pointer type in the mix. So getObject is actually returning a BasePtr that boost.python knows how to convert to a RefPtr<BasePtr>. See the previous thread for all the details.

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import_array() evokes illegal hardware instruction on MAC OS
by Qinfeng(Javen) Shi Oct. 28, 2006

Oct. 28, 2006

Dear All, I used import_array() in c extension of python wrapped by boost. It works well on linux. Then I recompiled it in MAC OS (by bjam) without any error. But when I imported it in python on MAC OS, it reported a error. It seems that import_array() evoked the error. If I delete import_array(), then import it, it won't report the error. But I need import_array() to handle numpy.array. Does anybody can help me? -------------------error------------------ >> import coverTree zsh: illegal hardware instruction -----------------c extension------------ namespace ar=boost::python::numeric; BOOST_PYTHON_MODULE(coverTree) { import_array(); //ar::array::set_module_and_type("numpy", "ndarray"); } -- Qinfeng(Javen) Shi Research School of Information Sciences and Engineering Australian National University Locked Bag 8001 Canberra ACT 2601 -- Qinfeng(Javen) Shi Research School of Information Sciences and Engineering Australian National University Locked Bag 8001 Canberra ACT 2601

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Re: [C++-sig] Embedding...
by Stefan Seefeld Oct. 27, 2006

Oct. 27, 2006

Beau Sapach wrote: > That seems to have worked, I manually added the BOOST_PYTHON_DECL macro to > the 4 files and now it links just fine. Thanks! Strangely though, my app Great ! David, is it OK for this patch (see previous mail) to be applied to both, HEAD, as well as the 1_34 branch ? > can't link into the DLL at runtime unless it's in the same folder, even > though the DLL is on the PATH and the LD_LIBRARY_PATH. And finally, the > program is breaking within the first call to import: > > boost::python::object main = boost::python::import("__main__"); > > it breaks on: > > python::handle<> module(python::borrowed(PyImport_AddModule(n))); > > saying: > > Unhandled exception at 0x1e079547 in boostapp.exe: 0xC0000005: Access > violation reading location 0x00000004. That's very strange. Can you run the boost.python test suite ? I'd strongly suspect your build system / code to be the culprit, unless you can prove the contrary. :-) (And yes: in order for anybody to be able to help you further a test case is needed, making the failure reproducible, at least to those who run boost on the same platform as you.) Regards, Stefan -- ...ich hab' noch einen Koffer in Berlin...

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How to compile boost.python with '-fPIC' option
by Grant Tang Oct. 27, 2006

Oct. 27, 2006

I am trying to compile boost.python for a static libboost_python.a library, I need compile it with -fPIC option, but in the Jamfile I can not figure out a way to add this option? Can somebody help me? Thx -- Grant

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