Mailman 3 April 2004 - Cplusplus-sig

multiple registrations of to-Python converter warning
by Lutz Paelike April 26, 2004

April 26, 2004

Hi, I use Boost.Python to embed Python into another program. I wrapped some C++ classes to be able to share data. From time to time i get the following warning: sys:1: RuntimeWarning: to-Python converter for class MySpecialClass already registered; second conversion method ignored. MySpecialClass is my wrapped class in this case. Obviously something is called twice but i have no clue what. A first guess was the initModulename() but i'm pretty sure that's not the case. The program works without problems, but i would like to know how/when this warning occurs. Any hints into the right direction would be fine. Thank you, Lutz ------------------<snip>---------------- Lutz Paelike Stargarder Str. 47 10437 Berlin ++(49)-(0)30-44009581 mail: lutz(a)fxcenter.de lutz_p(a)gmx.net pgp key id: 0xA7B25440 pgp key server: x-hkp://wwwkeys.pgp.net pgp fingerprint: 9064 F4E1 D754 C2FF 1619 305B C09C 5A3B 57F3 BF04 ------------------<snip>----------------

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Re: Re: a python property being a reference
by Alex April 25, 2004

April 25, 2004

>> add_property("toto", &CToto::get_toto) >> >> with CToto::get_toto returning an object reference >> it doesn't work caus it needs a return value policy >> how can i give a return value policy in add_property like in def ? >Look in the reference manual for make_getter and make_setter. I can make a "def_readonly" like with make_getter but how can I make a regular property with that ? I want to use my own "get" fucntion, not the default one boost.python can make with make_getter Alex

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FYI: Mac OS 10.3 Xcode 1.2
by Ralf W. Grosse-Kunstleve April 24, 2004

April 24, 2004

With Apple's latest Xcode tools v1.2, under OS 10.3.3, all Boost.Python tests compile, link and run without any problems, with full optimization. For me this is the first time ever. (With the older Xcode tools I saw errors while linking some tests.) This is with a boost CVS snapshot from yesterday. My build system is SCons based; I have not tried bjam. Ralf __________________________________ Do you Yahoo!? Yahoo! Photos: High-quality 4x6 digital prints for 25� http://photos.yahoo.com/ph/print_splash

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string being deleted causes crash
by andrew April 24, 2004

April 24, 2004

I'm using boost python 1.31.0, python 2.2/2.3 (both had the same problem), and msvc7 to wrap up my library. I'm in Windows XP I have many functions that takes a std::wstring, sometimes in random different places the program crashes. If I run it with MSVC's debugger, I find that the passed string is attempting to be deleted. I have found that my problem is the same as described here: http://mail.python.org/pipermail/c++-sig/2003-June/004220.html However I tried both of the suggested fixes in that thread (make sure compiling in debug mode if using debug bpl lib/release if using release bpl lib, and using bjam) All of these resulted in the same problem, just on different calls. Anyone know what to do? Andrew

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Wrapping Arrays?
by Franz Kaiser April 23, 2004

April 23, 2004

Hi, I just wanted to ask if someone could give me a little example of how to wrap a C++ array. I looked at the indexing stuff in the documentation, but it doesn't tell me much. F.

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How to access a custom module from embedded Python?
by Peter April 22, 2004

April 22, 2004

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

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Re: MSVC and exposing virtual member functions
by Xavier April 22, 2004

April 22, 2004

Thanks for your help guys, I'm glad it was something simple. I'm getting a whole heap of linking errors now, but I'll look through the tutorial again to see what I've missed. - Xavier

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efficient vector wrapping
by Neal D. Becker April 21, 2004

April 21, 2004

I'm using vector_indexing_suite to wrap stl::vector. Suppose I have a function F, which outputs to a vector like so: void F (std::vector& out); Suppose in python I want the output to be written to a slice of a vector, so that there is an offset "d" from the start of the python vector. With stl-style iterators this would be trivial, but this is python, not c++. One possibility is: v1 = vector (10) d = 2 F (v1) v2 = vector (len(v1)+d) v2[d:] = v1 Is there a more efficient, and still python-friendly, approach?

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MSVC and exposing virtual member functions
by Xavier April 21, 2004

April 21, 2004

I know similar problems have been covered before, but I couldn't find anything about the error I'm getting. I've been wading around the documentation for a while and find myself going in circles :S I compiled boost 1.31 using VC6, with the appropriate fix in inheritance.hpp I've attached the code I'm trying to get to compile, the error I'm getting is: inheritance.hpp(100) : error C2243: 'type cast' : conversion from 'class BaseWrap *' to 'class Base *' exists, but is inaccessible I pretty much copied the code from the tutorial. Could the part I commented out during the boost compile be causing this error? On a slightly unrelated note, I downloaded the MSVC 2003 Toolkit from MS with the 7.1 compiler - Can I just copy the files in there over the top of my VC6 files, or do I need to do any extra setup? Also, as a MSVC project, should I be compiling this sort of thing as a DLL? - Xavier #include <boost/python.hpp> using namespace boost::python; class Base { public: virtual int f() = 0; }; int call_f(Base& b) { return b.f(); } class BaseWrap : Base { BaseWrap(PyObject* self_) : self(self_) {} int f() { return call_method<int>(self, "f"); } PyObject* self; }; BOOST_PYTHON_MODULE(test_module) { class_<Base, BaseWrap, boost::noncopyable>("Base", no_init) ; def("call_f", call_f); }

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boost python and python help
by Ben Young April 21, 2004

April 21, 2004

I know it is not a major issue, but did you know that free functions in boost::python ified modules do not show up in the interactive help. Looking into this (pydoc lines 558) it appears that for the free functions >>> inspect.isroutine(function) passes, but >>> if inspect.isbuiltin(function) or inspect.getmodule(function) is module: fails, mainly because inspect.getmodule(function) returns None. I'm not sure if there is a nice solution, as the functions are of a special type, but this can be quite annoying when playing around with new APIs. Cheers, Ben Young

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