Mailman 3 August 2004 - Cplusplus-sig

How to capture stdout/stderr?
by Peter Aug. 28, 2004

Aug. 28, 2004

Hi, I am trying to capture stdout and stderr from Python using boost.python. I can do it using the Python C API but can't work out the correct way to do it using the boost wrappers. Using the C API I'd do something like: PyObject* pObj = Py_InitModule("stdout", my_methods); PySys_SetObject("stdout", pObj); PySys_SetObject("stderr", pObj); How should I do this with boost? Thanks Peter

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How to capture stdout/stderr?
by Peter Aug. 28, 2004

Aug. 28, 2004

Hi, I am trying to capture stdout and stderr from Python using boost.python. I can do it using the Python C API but can't work out the correct way to do it using the boost wrappers. Using the C API I'd do something like: PyObject* pObj = Py_InitModule("stdout", my_methods); PySys_SetObject("stdout", pObj); PySys_SetObject("stderr", pObj); How should I do this with boost? Thanks Peter

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Slice tests failing on MSVC 7.1, 8.0
by Jonathan Brandmeyer Aug. 27, 2004

Aug. 27, 2004

According to the automated regression testers here: http://www.meta-comm.com/engineering/boost-regression/developer/python_.html The slice test is failing on MSVC 7.1 and 8.0. First off, do you expect them to pass on these compilers? If so, the problem is that C++ functions that take a boost::python::slice argument raise a Boost.Python.AgumentError when called with a Python-created slice. The errors in the log take the form: ArgumentError: Python argument types in slice_ext.check_slice_get_indicies(slice) did not match C++ signature: check_slice_get_indicies(class boost::python::slice) Any ideas? Thanks, -Jonathan

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Implicitly converting HeldTypes from Derived to Base?
by Chad Austin Aug. 25, 2004

Aug. 25, 2004

I have a situation like this: // foo.cpp #include <boost/intrusive_ptr.hpp> #include <boost/python.hpp> using namespace boost; using namespace boost::python; class RefCounted { public: RefCounted() { _count = 0; } virtual ~RefCounted() { } int _count; }; void intrusive_ptr_add_ref(RefCounted* ptr) { ++(ptr->_count); } void intrusive_ptr_release(RefCounted* ptr) { if (--(ptr->_count) == 0) { delete ptr; } } class A : public RefCounted { }; class B : public A { }; typedef intrusive_ptr<A> APtr; typedef intrusive_ptr<B> BPtr; void foo(APtr a) { } BOOST_PYTHON_MODULE(foo) { class_<A, APtr>("A"); class_<B, BPtr, bases<A> >("B"); def("foo", &foo); // Without implicitly_convertible, foo(B()) fails with: // // Traceback (most recent call last): // File "<stdin>", line 1, in ? // Boost.Python.ArgumentError: Python argument types in // foo.foo(B) // did not match C++ signature: // foo(boost::intrusive_ptr<A>) implicitly_convertible<BPtr, APtr>(); } Is there any way that implicitly_convertible call from the Derived HeldType to the Base HeldType can be made automatic? Thanks, Chad

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Re: [C++-sig] Re: yet another: TypeError: No to_python (by-value) converter found for C++ type:
by tALSit de CoD Aug. 24, 2004

Aug. 24, 2004

Hmm... i've been trying to understand it, i've read the docs... but... ummm... i can't quite understand it very well... Does this mean that when my class does: const std::vector <cNodeDescriptor *> cRegistry::getDescriptors (); i have to replace that with this: boost::indirect_iterator<std::vector<cNodeDescriptor*>::iterator> cRegistry::getDescriptors (); Or am i just totally missing the point? Most of the template magic voodoo still baffels me... :D David Abrahams wrote: > "tALSit de CoD" <talsit(a)talsit.org> writes: > > >>Hey guys! >>I know this has been answered to some extent before, but I just can't get to grips with it, so i know i'm doing something wrong... >> >>I export the following: >> >>//---------------------------------------------------------------- class_ <cNodeDescriptor, boost::noncopyable> ("cNodeDescriptor", no_init) >> .def ("getClassId",&cNodeDescriptor::getClassId) >> .def ("getName",&cNodeDescriptor::getName, return_value_policy >><copy_const_reference> ()) >> ; >> >>//---------------------------------------------------------------- class_ <std::vector <cNodeDescriptor *> > ("cNodeDescriptorList") >> .def ("__iter__", iterator <std::vector <cNodeDescriptor *> > ()) ; >> >>And then, in python, i grab a cNodeDescriptorList, and when i try to iterate through it, it spits out: >> >>TypeError: No to_python (by-value) converter found for C++ type: class kikura::cNodeDescriptor * >> >>So... what am i doing wrong? >> >>If more info is needed, i'd be glad to supply it... > > > Try using range > (http://www.boost.org/libs/python/doc/v2/iterator.html#range-spec) with a functions that return > boost::indirect_iterator<std::vector<cNodeDescriptor*>::iterator> wrapped around the vector's begin() and end(). > (http://www.boost.org/libs/iterator/doc/indirect_iterator.html) > > HTH, // talsit.org

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pyste question
by Andrew Sutton Aug. 24, 2004

Aug. 24, 2004

hi... pyste noob here. i'm building some python interfaces for a library i've written and i'm trying to make the exposed python classes as "python-friendly" as possible (like nice iteration support). to do this, i'm trying to inject methods into my classes using add_method(). unfortunately, pyste is not finding the methods i'm requesting to be added. it seems to be related to the fact that the methods i'm having pyste add to the class aren't located in the same header file as the class. for example: [list.hpp] class list { ...; } [list_ext.hpp] iterator list_iterator(); [list.pyste] List = Class("list", "list.hpp") ListIterator = Function("list_iterator, "list_iterator.hpp") add_method(List, "list_iterator", "__iter__") or something very similar to that. it seems that the behavior of add_method only looks for methods defined in the file with the class - because this doesn't work with includes or added code either - quite frustrating. am i going about this completely wrong? any help would be appreciated. thanks in advance. andrew sutton asutton(a)cs.kent.edu

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boost.python extract and smart-pointer
by Baptiste Lepilleur Aug. 23, 2004

Aug. 23, 2004

I'm running in some trouble with extract during unpickling of null smart-pointer. I have registered a intrusive_ptr based smart-pointer which works greatly. During pickling, my null smart-pointer converted into None. During unpickling, when I use extract<MyPtrType> on a null smart-pointer I get a conversion error saying that there is no conversion from NoneType to MyPtrType. Is this a known issue, or did I miss something ? As a work-around I tried to test if tuple[1] was None, but couldn't figure out how to do that in C++. Any tips ? Baptiste.

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Optimize vector_indexing_suite set_slice
by Neal D. Becker Aug. 19, 2004

Aug. 19, 2004

vector_indexing_suite set_slice does: 1) erase 2) insert Shouldn't this be optimized to simply do copy?

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RE: [C++-sig] Re: creating an instance of a class_<> object in c+ + an d exporting it to python
by Max Khesin Aug. 19, 2004

Aug. 19, 2004

> Max Khesin <MKhesin(a)liquidnet.com> writes: > > > Maybe I missed something, but I think this should work for you: > > > > class_<A, A*, boost::noncopyable> classA("A", noinit);// > this is the class > > object - only one registration! > > classA.def("f1", &A::f1) > > .... > > ; > > CPPObj cppObj; > > object instanceOfA1 = classA(&cppObj);// multiple instances > > object instanceOfA2 = classA(&cppObj); > > > Or: > > object classA > = class<A, A*, boost::noncopyable>("A", noinit) > .def("f1", &A::f1) > ... > ; In style! Nice. Also the OP wants to "create an instance of a wrapped object "A", initializing it using a pointer to an existing instance of a C++ A object." so I assume something like this is needed: object classA = class<A, A*, boost::noncopyable>("A", CPPObj*) .def("f1", &A::f1) ... ; > Dave Abrahams > Boost Consulting > http://www.boost-consulting.com > > _______________________________________________ > C++-sig mailing list > C++-sig(a)python.org > http://mail.python.org/mailman/listinfo/c++-sig > This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the system manager. This message contains confidential information and is intended only for the individual named. If you are not the named addressee you should not disseminate, distribute or copy this e-mail.

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Re: Newbie vector_indexing_suite Link Errors
by David Brownell Aug. 18, 2004

Aug. 18, 2004

I was attempting to compile and link vector_indexing_suite.cpp, located in the python\test directory. It looks like #define'ing BOOST_PYTHON_STATIC_LIB was all I needed. Seems strange that I didn't have to #define this until I started working with the vector_indexing_suite. Thanks for your help! David Brownell "David Abrahams" <dave(a)boost-consulting.com> wrote in message news:<uu0v02sim.fsf(a)boost-consulting.com>... > "David Brownell" <groups(a)DavidBrownell.com> writes: > > > I just discovered vector_indexing_suite, and am trying to compile the sample > > application that is linked from the documentation. > > Which one, please? Linked from where in the documentation? > > > When I compile the C++ > > code, > > You mean when you try to link. > > > I get the following unresolved externals: > > > > __declspec(dllimport) void __cdecl > > boost::python::objects::register_dynamic_id_aux <snip> > > __declspec(dllimport) void * __cdecl > > boost::python::objects::find_static_type <snip> > > __declspec(dllimport) public: __thiscall > > boost::python::converter::detail::arg_to_python_base::arg_to_python_base > > <snip> > > __declspec(dllimport) void * __cdecl > > boost::python::objects::find_dynamic_type <snip> > > __declspec(dllimport) class boost::python::api::object const & __cdecl > > boost::python::objects::identity_function <snip> > > __declspec(dllimport) struct _object * __cdecl > > boost::python::objects::make_nurse_and_patient <snip> > > __declspec(dllimport) void __cdecl > > boost::python::objects::stop_iteration_error <snip> > > > It seems strange to me that the symbols are decoared with dllimport rather > > than dllexport, but I didn't see any unusual preprocessor magic going on in > > the code or described in the documentation that would ensure that these > > symbols are exported rather than imported. Is there something that I am > > missing to compile the example? > > > > Compiler: Microsoft Visual Studio v7.1 > > OS: Win XP > > Boost: linking with $(PYTHON_ROOT)\libs\python23.lib and > > libboost_python-vc71-mt-gd-1_31.lib (which was compiled using bjam) > > Python: 2.3 > > Did you use bjam to build the "sample application?" If not, do so. > > -- > Dave Abrahams > Boost Consulting > http://www.boost-consulting.com

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