Mailman 3 September 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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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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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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Exposing c++ classes with static arrays using Boost.Python and py++
by Abhi Oct. 3, 2006

Oct. 3, 2006

While running py++ on a class with a static array inside it, py++ generates Boost.Python bindings using a derived class for the original C++ class. Let me illustrate with the help of the following example: class AttributesTest { public: int staticIntArray[10]; }; Notice this class has an array inside it Running py++ generates the following code, with a wrapper class that derives from the AttributesTest class. struct AttributesTest_wrapper : AttributesTest, bp::wrapper< AttributesTest > { AttributesTest_wrapper(AttributesTest const & arg ) : AttributesTest( arg ) , bp::wrapper< AttributesTest >() {} AttributesTest_wrapper( ) : AttributesTest( ) , bp::wrapper< AttributesTest >() {} pyplusplus::containers::static_sized::array_1_t< int, 10 > pyplusplus_staticIntArray_wrapper(){ return pyplusplus::containers::static_sized::array_1_t< int, 10 >( staticIntArray ); } }; and BOOST_PYTHON_MODULE(PYPP_YodaPacketCommon){ if( true ){ typedef bp::class_< AttributesTest_wrapper > AttributesTest_exposer_t; AttributesTest_exposer_t AttributesTest_exposer = AttributesTest_exposer_t( "AttributesTest" ); bp::scope AttributesTest_scope( AttributesTest_exposer ); AttributesTest_exposer.def( bp::init< >()[bp::default_call_policies()] ); pyplusplus::containers::static_sized::register_array_1< int, 10, bp::default_call_policies >( "__array_1_int_10" ); AttributesTest_exposer.add_property( "staticIntArray" , bp::make_function( (pyplusplus::containers::static_sized::array_1_t< int, 10 > ( AttributesTest_wrapper::* )( ) )(&AttributesTest_wrapper::pyplusplus_staticIntArray_wrapper) , bp::with_custodian_and_ward_postcall< 0, 1, bp::default_call_policies >() ) );; Note that it maps the python name "AttributesTest" to the derived class AttributesTest_wrapper. Why not just keep it simple and rather than creating a derived class just map the variable "staticIntArray" via a global method, such as: .add_property( "staticIntArray" , bp::make_function( (&::someglobal_staticIntArray_wrapper) , bp::with_custodian_and_ward_postcall< 0, 1, bp::default_call_policies >() ) );; and define the someglobal_staticIntArray_wrapper method as: pyplusplus::containers::static_sized::array_1_t< int, 10 > someglobal_staticIntArray_wrapper(){ return pyplusplus::containers::static_sized::array_1_t< int, 10 >( staticIntArray ); } Is there any drawback with just mapping the array variable to a global method rather than mapping the whole class. thanks - Abhi

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Re: [C++-sig] (Philip Austin) PyArray_SimpleNewFromData(, PyArray_FLOAT, ) can't get c array in c extension?
by Qinfeng(Javen) Shi Sept. 30, 2006

Sept. 30, 2006

Hi Philip, I did as following, but it did not work. --------------------------------c extension----------------------- PyObject * testCreatArray() { float fArray[5] = {0,1,2,3,4}; PyArrayObject * c = (PyArrayObject*)PyArray_SimpleNewFromData(1,&m,PyArray_FLOAT,fArray); return (PyObject *)c; } ---------------------------result------------- >>> import hello >>> import numpy >>> list1 = range(5); >>> alist = hello.testCreatArray() >>> print alist [ 4.83833291e-34 -2.52239988e-05 -2.52361860e-05 0.00000000e+00 0.00000000e+00] >>> -- Qinfeng(Javen) Shi Research School of Information Sciences and Engineering Australian National University Locked Bag 8001 Canberra ACT 2601

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Another problem with split_module
by Ganssauge, Gottfried Sept. 29, 2006

Sept. 29, 2006

Hi Roman, as you may remember I'm generating function wrappers for functions expecting pointers to callback functions along with an instance pointer of type void. How do I make sure these wrappers are generated to the same file as the registration of the wrapper? Consider the following test: In single file mode this produces a working test module. In split file mode the WRAPPER_CODE is generated to test_wrapper.main.cpp whereas the registration is generated to test_wrapper_free_functions.pypp.cpp. test.hpp --- 8>< ------ ><8 --- void test (void *instance, void (*callback)(void *)); --- 8>< ------ ><8 --- test.py --- 8>< ------ ><8 --- # # Wrapper code for void test (void (*test)(void *)); # WRAPPER_CODE = """ void wrap_test_callback (void *instance) { boost::python::call<void> (reinterpret_cast<PyObject *> (instance)); static void test_wrapper (PyObject *callback) { test ( callback && (callback != Py_None)? wrap_test_callback: 0, callback); } """ import os from pyplusplus import \ module_builder from pygccxml.declarations.calldef import \ argument_t from pygccxml.declarations.cpptypes import \ dummy_type_t, \ pointer_t # PyObject * pyobject_type = pointer_t (dummy_type_t ("PyObject")) mb = module_builder.module_builder_t( ["test.hpp"] ) test = mb.free_function (name = "test") test.arguments = [ argument_t (name = "callback", type = pyobject_type) ] test.name = "test_wrapper" test.rename ("test") # this goes to the wrong source file :-( mb.add_declaration_code (WRAPPER_CODE) mb.build_code_creator( module_name='test_wrapper' ) mb.split_module( '.' ) --- 8>< ------ ><8 --- Cheers, Gottfried

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PyArray_SimpleNewFromData(, PyArray_FLOAT, ) can't get float c array in c extension?
by Qinfeng(Javen) Shi Sept. 29, 2006

Sept. 29, 2006

Dear All, I used PyArray_SimpleNewFromData to transfer a float c array data into numpy.ndarray. But it got the wrong array values. Any suggestion? Thanks in advance! ---------------------------hello.c------------- PyObject * testCreatArray() { float fArray[5] = {0,1,2,3,4}; intp m = 5; PyObject * c = PyArray_SimpleNewFromData(1,&m,PyArray_FLOAT,fArray); return c; } --------------------------result-------------------- >>> import hello >>> import numpy >>> list1 = range(5); >>> alist = hello.testCreatArray() >>> alist array([ 0.00000000e+00, -2.65695271e-05, 4.64483736e-34, 4.34402524e-44, -8.06840762e-06], dtype=float32) >>> -- Qinfeng(Javen) Shi Research School of Information Sciences and Engineering Australian National University Locked Bag 8001 Canberra ACT 2601

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[Graph] BGL python extension SVN version didn't link
by John Reid Sept. 29, 2006

Sept. 29, 2006

Hi, I tried to build the BGL from the latest SVN version and had some link errors to do with expat. My changes to fix these were the following: Add the following to the $(EXTRA_REQUIREMENTS) in bgl-python\build\Jamfile <define>XML_STATIC and add <define>XML_STATIC to the requirements for lib expat in bgl-python\vendor\expat-2.0.0\Jamfile I hope that helps someone or else someone can point out what I was doing wrong in the first place. FWIW I'm using MSVC8 with boost RC_1_34_0 Cheers, John.

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boost::python problem with std::string
by Sergey Makovkin Sept. 29, 2006

Sept. 29, 2006

Hello! I want to use Boost.python in my program but I have a problem. When I call a C++ function with std::string argument (or const std::string& ) from python, boost.python crashes! I don't know what to do and I hope you can help me. Here is a link to the source code which demonstrates the problem: http://www.powerfly.ru/bug.zip To compile it, you need MS Visual Studio 2005, Python 2.4 and Boost.Python 1.33 or later. -- Sergey A. Makovkin

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Problem with PyMethodDef and non-static functions
by Jon Kristensen Sept. 28, 2006

Sept. 28, 2006

Hello list! I'm using Python/C to be able to have simple Python scripts in my application. I was free of problems until I switched from using static and global functions to using non-static class methods: python.cpp:101: error: argument of type ‘PyObject* (Python::)(PyObject*, PyObject*)’ does not match ‘PyObject* (*)(PyObject*, PyObject*)’ After some time I understood that this was a problem that a little tweaking around wouldn't solve. So I want to ask you guys if you can describe how to get around this. I wouldn't want to add any additional dependencies such as SWIG or Boost. Please also note that I'm not that experienced with Python. And I want to keep this as clean/simple as possible! :-) Thanks in advance! -- Jon Kristensen

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