Mailman 3 December 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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Supplying a Python base class when wrapping a C++ class...
by Alex Mohr April 19, 2007

April 19, 2007

I'd like to wrap a C++ class and have the generated python wrapper class derive from a Python class. I know I can use bases<> to have my wrapped class derive from the class objects associated with the C++ types I specify in bases<>, but in this instance, I want to derive my wrapper class from a Python class that was not generated by boost.python. From looking at the code, it seems like it would be some work to add this capability. (Is anyone working on something like this?) As a workaround, does anyone know a way that I could perhaps hack this in after the Python class is created? That is, can I change the Python base classes of a Python class at runtime? Thanks, Alex

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Extending Python with not-basic-c++
by Son, Serguei Dec. 28, 2006

Dec. 28, 2006

David For a great example of embedding Python in a game, check out Civilization IV.

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Re: [C++-sig] Your confirmation is required to join the C++-sig mailing list
by sai bharadwaj Dec. 23, 2006

Dec. 23, 2006

-- Bharadwaj Send free SMS to your Friends on Mobile from your Yahoo! Messenger. Download Now! http://messenger.yahoo.com/download.php

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Automatic conversions for const std::string&
by Gabriel Becedillas Dec. 22, 2006

Dec. 22, 2006

I have a lot of functions returning "const std::string&". Every time I wrap one of those I have to do it like this: class_.def("name", &someclass::bla, boost::python::return_value_policy<boost::python::copy_const_reference>() ); Is there a way to register a return value conversion for "const std::string&" so I can omit the "boost::python::return_value_policy<boost::python::copy_const_reference>()" every time I have to wrap this functions ? I wan't those strings to be copied to python as new strings (I don't want to hold a pointer to them). Thanks

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Re: [C++-sig] Boost.Python exception problems on AIX 5.3 (compiled with gcc 3.4.3, 64 bit)
by Ralf W. Grosse-Kunstleve Dec. 21, 2006

Dec. 21, 2006

> import sys > sys.setdlopenflags(0x00000002|0x00010000) > > Unfortunately this has no effect on the problem. Am I missing > something in how I'm setting this? Looks OK to me. No more ideas. A few years ago we had fatal EH problems using a certain Tru64 cxx release. The only way to resolve this was upgrading the compiler... __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

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Re: [C++-sig] Boost.Python exception problems on AIX 5.3 (compiled with gcc 3.4.3, 64 bit)
by J. Michael Owen Dec. 21, 2006

Dec. 21, 2006

Hi Ralf, Yeah, I use that dlopen hack myself on all the platforms where I'm using gcc. I've already tried this to handle this exception problem -- at least I think I've done it correctly. On AIX you can find the definitions for these things in /usr/include/dlfcn.h, where I see #define RTLD_NOW 0x00000002 /* Load object and dependents now. */ #define RTLD_GLOBAL 0x00010000 /* Make symbols in this module visible to other dlopens. */ So I've tried setting the following before importing my own test modules: import sys sys.setdlopenflags(0x00000002|0x00010000) Unfortunately this has no effect on the problem. Am I missing something in how I'm setting this? Mike. > Under Linux I'm importing all extension modules with RTLD_GLOBAL. This > is a very old workaround for exception handling problems similar to > what you describe, but I'm not sure about the details anymore (e.g. > which gcc was the trouble maker). > > This is roughly how I import our extensions: > > previous_dlopenflags = sys.getdlopenflags() > sys.setdlopenflags(0x100|0x2) > import myext > sys.setdlopenflags(previous_dlopenflags) > > The bit masks are platform specific, RTLD_GLOBAL | RTLD_NOW. If any of > this applies to AIX (?) you have to find out somehow what the correct > bit masks are. > > HTH, > Ralf

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Wrap a virtual function which returns a raw pointer
by Birgir Sigurjonsson Dec. 21, 2006

Dec. 21, 2006

Hi all. How can I wrap a virtual function which returns a raw pointer which will be managed from C++. I am embedding Python in my C++ application and I have the follwoing classes that I want to wrap in boost.python: In the code below the virtual function ALFactory::make() returns a pointer to an abstract class AL which is also wrapped with boost.python. I want to be able to override make() in python and in the implementation of this function create and return a new python subclass of my C++ AL. The lifetime of the created object is managed by the ALFactory. class ALFactory : private boost::noncopyable { public: ALFactory(const std::string& key); virtual ~ALFactory(); virtual AL* make() = 0; }; class AL : private boost::noncopyable { public: virtual ~AL(); protected: AL(); }; ################ Wrap classes class ALWrap : public AL, public boost::python::wrapper<AL> { public: ALWrap() : AL() {} }; class ALFactoryWrap : public ALFactory, public boost::python::wrapper<ALFactory> { public: ALFactoryWrap(const std::string& key) : ALFactory(key) {} AL* make() { return this->get_override("make")(); } }; ############ BOOST_PYTHON_MODULE(import_framework) { class_<ALWrap, boost::noncopyable>("AL") ; class_<ALFactoryWrap, boost::noncopyable>("ALFactory", init<std::string>()) .def("make", pure_virtual(&ALFactory::make), return_value_policy<manage_new_object>()) ; } ############### #### Python module code from import_framework import AbstractLoader, AbstractLoaderFactory class Ascii135Loader(AbstractLoader): def __init__(self): print self.__init__ class Ascii135LoaderFactory(AbstractLoaderFactory): def __init__(self, key): super(Ascii135LoaderFactory, self).__init__(key) print self.__init__ def make(self): return Ascii135Loader() register_this = Ascii135LoaderFactory("Ascii135") ####################### I get the following error. pure virtual method called ######################### I have browsed the documentation and not found a clear answer. I found the following quote on http://wiki.python.org/moin/boost.python/class decribes my problem. "There are several problems with the above arrangement, but the most important one is that if you keep the shared_ptr<U> alive longer than its corresponding Python object, calls to the Python-overridable virtual functions will crash, because they'll try to call through an invalid pointer." How can I solve this problem? Best regards, Birgir Sigurjonsson. DISCLAIMER: This message contains information that may be privileged or confidential and is the property of the Roxar Group. It is intended only for the person to whom it is addressed. If you are not the intended recipient, you are not authorised to read, print, retain, copy, disseminate, distribute, or use this message or any part thereof. If you receive this message in error, please notify the sender immediately and delete all copies of this message.

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