Mailman 3 April 2004 - Cplusplus-sig

trying to compile simple test example with numeric arrays
by Faheem Mitha April 13, 2004

April 13, 2004

Dear People, I'm trying to compile the following and getting errors. My C++ is rather rusty and I may be making other (non C++ related) errors. Specifically, I may not be understanding the proper use of the take function. Any help would be appreciated. Also, I notice when I remove `const' from the function argument `const numeric::array y' I get a whole scad of errors, for reasons that are not clear to me. I'd appreciate any enlightenment about this. Thanks. Faheem. ********************************************************************* #include <boost/python/numeric.hpp> #include <boost/python/tuple.hpp> #include <boost/python/extract.hpp> #include <boost/python/object.hpp> #include <boost/python/module.hpp> #include <boost/python/def.hpp> using namespace boost::python; // select designated rows from a 2d numeric array numeric::array rem_row(const numeric::array y, const tuple ind) { return extract<numeric::array>(y.take<tuple>(ind)); } BOOST_PYTHON_MODULE(arr) { def("rem_row", rem_row); }

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wrap_python.hpp errors on Mac OS X
by James Mastro April 12, 2004

April 12, 2004

I'm trying to use Boost.Python on Mac OS X 10.3.3, with boost 1.31.0. I finally got module building working right, and my Python objects can call into some wrapped C++ libraries of mine. But, I want to be able to go the other way, too. Have my C++ code call methods on the Python objects I create. But when I try to include <boost/python.hpp>, I get errors in the wrap_python.hpp file. The errors are: patchlevel.h: No such file or directory Python.h: No such file or directory The Python.h error I can easily fix. For the other, just commenting out the include of patchlevel.h seemed like a grand idea. But then I start getting compile errors in convertible.hpp (which might be happening even with my hacking in patchlevel.h) The boost.python site says it's known to work on 10.3, but it's not for me. Any ideas? I can use the Python/C API, of course, but Boost.Python looks much easier. -jim

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use boost.python to append my own script directory to sys.path, but failed!
by 千里马肝 April 12, 2004

April 12, 2004

hello! I write code to instead of PyRun_SimpleString("import sys\nsys.path.append(...)"), like this: _main_module = object(handle<>(borrowed(PyImport_AddModule("__main__")))); _main_namespace = dict(_main_module.attr("__dict__")); _sys_module = object(handle<>(PyImport_ImportModuleEx("sys", _main_namespace.ptr(), _main_namespace.ptr(), NULL))); _sys_namespace = dict(_sys_module.attr("__dict__")); list sysPath(_sys_namespace["path"]); sysPath.insert(0, script_directory); <--- add the script directory _sys_namespace["path"] = sysPath; <--- is the sysPath is temporary value?!?! follow I want to import a custom module in the script directory, but it failed: custom_module = object(handle<>(PyImport_ImportModuleEx("a", _main_namespace.ptr(), _main_namespace.ptr(), NULL))); What can be the problem ?!?! thanks for reply!

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Re: [C++-sig] How to access a custom module from embedded Python?
by Peter April 10, 2004

April 10, 2004

Problem solved. My ignorance of how to use boost.python was to blame. I realized there is a fn named "inithello" that must be imported: PyImport_AppendInittab("hello", inithello); before Py_Initialize(); and later: object strRes(handle<>(PyRun_String( "from hello import *\n" "result = greet()\n", Py_file_input, main_namespace.ptr(), main_namespace.ptr()) )); const char* res = extract<const char*>(main_namespace["result"]); So simple! - Peter > I've just started using boost.python and have embedded a Python > interpretor in a test app. But how do I access a Python extension I > have created in the same app that embeds Python? > > e.g. I define a hello module > > BOOST_PYTHON_MODULE(hello) > { > def("greet", greet); > } > > and in the same code I embed Python: > > Py_Initialize(); > > handle<> main_module(borrowed( > PyImport_AddModule("__main__") )); > dict main_namespace(handle<>(borrowed( > PyModule_GetDict(main_module.get()) ))); > > And am stuck at the next step... how do I call hello.greet() from this > embedded Python instance? > > Thanks, > Peter > > > _______________________________________________ > C++-sig mailing list > C++-sig(a)python.org > http://mail.python.org/mailman/listinfo/c++-sig > >

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BPL and multiple interpreters
by Niall Douglas April 9, 2004

April 9, 2004

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Having just recompiled everything to use the dynamic object python, it now turns out that on Linux at least, python v2.3 recalls the init<Lib>() function for any python extension modules imported into a new interpreter. This is despite the documentation for Py_NewInterpreter saying that this is not the case. Surely though people on this list have noticed this before? If someone has used multiple interpreters with BPL and not found this, please do say. Otherwise, I suppose I should submit a bug report. Cheers, Niall -----BEGIN PGP SIGNATURE----- Version: idw's PGP-Frontend 4.9.6.1 / 9-2003 + PGP 8.0.2 iQA/AwUBQHbQ08EcvDLFGKbPEQIUyQCbB69HCkWCdONaUkRKhkS2oVFivMsAnR0o cw9HY5yhODNa9nWENtqqKWzn =fkbS -----END PGP SIGNATURE-----

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Python differences on Windows and Linux
by Niall Douglas April 9, 2004

April 9, 2004

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 When creating a new interpreter using Py_NewInterpreter, on Windows I need to reimport my BPL based bindings in the new environment but if I try this on Linux I get BPL failing its "I don't like being imported twice" assertion test. Is this behaviour known and does anyone know why it's happening? Could it be related to my BPL based bindings being linked against a static library python on linux versus a dynamic library python on Windows? (I have wondered what the effects of having copies of python disjointed across different ELF binaries might be, especially if they're passing python structures being each other). Cheers, Niall -----BEGIN PGP SIGNATURE----- Version: idw's PGP-Frontend 4.9.6.1 / 9-2003 + PGP 8.0.2 iQA/AwUBQHXi5sEcvDLFGKbPEQLOLgCg9PO5wWeucGtXFN9+WLMYwkmJbGUAoNFL fcjxFM/ifNM4S+tOMTeqOy6e =FNhv -----END PGP SIGNATURE-----

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python copying of boost-python objects
by Neal Becker April 9, 2004

April 9, 2004

I'm having a hard time figuring out how python handles copying of boost-python objects. In particularly, I want to wrap stl vector objects. What happens when I do x1 = x2[:] or use python copy()? Can/should I do something to control it to ensure large vector copies are efficient?

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should (how) I use Python to run my c++ classes
by bert＠isiosf.isi.it April 8, 2004

April 8, 2004

Hi all, I'm not a Python user, but I've read something and it seems very interesting. I'm expecially interested in it's interplatform nature also reguarding GUI (though Tkinter.) I've already written a lot of classes for medical image processing, and now I'm using qt as GUI to put all together. But, first of all, qt isn't free under windows, plus I'm encountering several troubles in putting together some libraries. So I though to Python as a possible language by which to write the GUI (Tkinter) and call my c++ classes. I've read quickly several parts of "learning Python" (oreilly) and I got my idea is feasible and even suggested in the introduction. But I don't know at all how to realize it... Of corse I now I'll have to read a lot, but it would be nice to have a simple example of a minimal python program calling a c++ class, maybe after clicking on a tk button. In this way I would understand if at least it can be useful for me before to start a timekeeping study. Any suggestion will be appreciated, thank you very much, Alberto

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[boost-python] overloading problem
by Neal D. Becker April 8, 2004

April 8, 2004

I'm having trouble with overloading. It seems to work for default args, but not for a family of fncs with common prefix. This is on gcc-3.3.3. #include <boost/python/module.hpp> #include <boost/python/def.hpp> #include <boost/python/class.hpp> #include <boost/python/init.hpp> #include <boost/python/overloads.hpp> using namespace boost::python; struct george { void wack_em(int a) {} void wack_em(int a, int b) {} }; BOOST_PYTHON_MEMBER_FUNCTION_OVERLOADS(george_overloads, wack_em, 1, 2) BOOST_PYTHON_MODULE (GEORGE) { class_<george> ("george") .def("wack_em", &george::wack_em, george_overloads()) ; } g++ -c Test3.cc -I/usr/include/python2.3 Test3.cc: In function `void init_module_GEORGE()': Test3.cc:19: error: no matching function for call to ` boost::python::class_<george, boost::python::detail::not_specified, boost::python::detail::not_specified, boost::python::detail::not_specified> ::def(const char[8], <unknown type>, george_overloads)'

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wrapping constructor
by Neal D. Becker April 8, 2004

April 8, 2004

Using boost-python I have a class with non-default constructor. I don't want to expose this constructor to python, but want to wrap it in a new interface. Is this OK? (No ownership issues...) I'm assuming copying the object is not terribly expensive, or won't happen that often. class X { X (something something) }; X MakeX (some args more suitable for python) { return X (use above constructor); } BOOST_PYTHON_MODULE(X_wrap) { class_<X> ("X", no_init); def ("MakeX", MakeX); }

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