Mailman 3 October 2002 - Cplusplus-sig

A larger gold balance!
by Nobody Oct. 30, 2002

Oct. 30, 2002

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MacOSX building... of shared libraries...
by Rene Rivera Oct. 29, 2002

Oct. 29, 2002

I've been working on the "darwin-tools.jam" toolset to try and get Boost & Boost.Python working on MacoOSX. (Thanks to Ralf for access to the MacOSX machine :-) ...And here are some conclusions... The toolset is minimally working for standard compilation. But the compilation of shared libraries is limited at best. That is the toolset is working to generate both "dylib" and "bundle" type shared libraries. The problem is... that this doesn't work for Boost.Python in it's current form. After much reading and many different attempts I've learned some things about MacOSX. 1. "dylib" shared libraries are what I would consider standard shared libraries in the Unix sense. 2. "bundle" shared libraries are what Apple thinks application plugins should be like. That's all nice, but the way Apple changed the compiler, linker, and loader to implement that makes the above arrangement problematic for code like Boost.Python. The problems are: a. "dylib" shared libraries don't seem to support resolving of symbols back from the application loading the library. Like the AIX loading problem. ...not a problem, after all that's what "bundles" are for, right? but... b. "bundle" shared libraries do resolve the symbols from the loader context as long as you specify the loader binary when linking, using the -bundle_loader flag. And the current build system files in CVS do this when using the darwin toolset. But bundles have one limitation, they can't depend on other bundles. So if I build boost_python as a bundle, other python extensions can't use it as a dependence as one would in Linux. So I have two options, neither of which work for Boost.Python. So if anyone has suggestions or insights I would welcome them ;-\ Or for that matter.. is there any way to rearrange the Boost.Python code so that is doesn't need to link against the python executable? Which would turn it into what Apple calls a framework, to break the inter-dependence problem. -- grafik - Don't Assume Anything -- rrivera(a)acm.org - grafik(a)redshift-software.com -- 102708583@icq - Grafik666@AIM - Grafik(a)jabber.org

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call policies
by Stefan Seefeld Oct. 28, 2002

Oct. 28, 2002

hi there, I'm reading up on call policies but I'm not sure my case is covered there: I'v got an object handed back from a factory call. I pass this object to another object where the second one takes over ownership: Foo *foo = FooFactory(); Bar *bar = BarFactory(foo); (with either Bar *BarFactory(Foo *); or Bar *BarFactory(auto_ptr<Foo>); signature. How do I express that in boost.python ? The 'custody_and_wart' policy expects two arguments, the object to be consumed as well as the consuming one. In my case the consumer is created in the call. Which policy do I need ? Thanks, Stefan

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Re: [C++-sig] type convert: python file <-> C++ FILE*
by Liwei Peng Oct. 28, 2002

Oct. 28, 2002

Hi, For converting python file to/from C++ FILE*, I tried the suggested code. It didn't work. I got the same error message like before. Here is my c++ code: ----------------------------------------- #include <boost/python.hpp> namespace python = boost::python; struct FILE_to_pyfile { static PyObject* convert(FILE const& x) { return PyFile_FromFile((FILE*)(&x), "", "", NULL); } }; FILE* getfile(const char* fname) { printf("openning file: %s\n", fname); FILE* f = fopen(fname, "w"); fprintf(f, "initial words\n"); return f; } BOOST_PYTHON_MODULE(numbermod) { python::to_python_converter<FILE, FILE_to_pyfile>(); python::def("getfile", getfile, python::return_value_policy<python::reference_existing_object>()); } -------------------------------- The only change I made to the suggested code is to cast "&x" (whose type is const FILE*) to 'FILE*". Without this, the code won't compile. Here is how I compile the code: --------------------------------- g++ -I/usr/include/python2.2 -fPIC -c number_wrap1.C g++ -shared number_wrap1.o -o numbermod.so -lboost_python -------------------------- I am using g++ 3.2, python 2.2.1. The error message from python code: ------------------------------------------- Python 2.2.1 (#1, Sep 9 2002, 09:26:21) [GCC 3.2 (Mandrake Linux 9.0 3.2-1mdk)] on linux-i386 Type "help", "copyright", "credits" or "license" for more information. >>> >>> from numbermod import * >>> f = getfile('hello.txt') Traceback (most recent call last): File "<stdin>", line 1, in ? TypeError: bad argument type for built-in operation >>> Can anyone please help me out? Thanks in advance, liwei __________________________________________________ Do you Yahoo!? Y! Web Hosting - Let the expert host your web site http://webhosting.yahoo.com/

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boost python v2: error with both default arg and pointer-return function
by Liwei Peng Oct. 28, 2002

Oct. 28, 2002

Hi, When using the boost python v2 to port a C++ member function like the following, I got an error with message "TypeError: bad argument type for built-in operation". class A; A* MyClass::foo(int n = 100); This only happens when a member function a) has a default argument; b) returns a pointer value. Here is my related C++ code: ---------------------------------------------- class Number { public: Number(int n); Number* copy(int n = 100); }; Number* Number::copy(int n) { printf("number of copies = %d\n", n); return this; } BOOST_PYTHON_MEMBER_FUNCTION_OVERLOADS(copy_overloads, copy, 0, 1); BOOST_PYTHON_MODULE(numbermod) { python::class_<Number> number_class("Number", python::init<int>()); number_class.def("copy", &Number::copy, python::return_internal_reference<>(), copy_overloads()); } ---------------------------------------------- python code: ---------------------------------------- from numbermod import * n = Number(10) n1 = n.copy() ---------------------------------------- error message: ---------------------------------------- Traceback (most recent call last): File "./test.py", line 19, in ? n1 = n.copy() TypeError: bad argument type for built-in operation Can anyone please tell me what's wrong? Thanks. Liwei __________________________________________________ Do you Yahoo!? Y! Web Hosting - Let the expert host your web site http://webhosting.yahoo.com/

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scope / namespace question
by Achim Domma Oct. 28, 2002

Oct. 28, 2002

Hi, I'm exposing a lot of classes called DrawableXXX and PathXXX. I want to put them in two sub-modules Drawable and Path, so that the python classes would be called Drawable.XXX and Path.XXX. As far as I understand the documentation of scope, I have to do something like this: BOOST_PYTHON_MODULE(myModule) { // register classes which are not part // of Drawable and Path // ... registerDrawableClasses(); registerPathClasses(); } void registerDrawableClasses() { scope drawable = ???; class_<DrawableXXX>("XXX") .def(... } void registerPathClasses() { scope path = ???; class_<PathXXX>("XXX") .def(... } In the documentation nested classes are used, so should I use an empty class like this? struct drawable_place_holder {}; scope drawable = class_<drawable_place_holder>("Drawable",no_init); Is that the way to go? greetings Achim

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fatal error C1204: compiler limit : internal structure overflow
by Achim Domma Oct. 27, 2002

Oct. 27, 2002

Hi, I get this error with VC7: "fatal error C1204: compiler limit : internal structure overflow". I remember that there should be a flag to change this internal structure, but I can't remember what the flag was and how to pass it to bjam. Any hint? thanks Achim

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test
by unix＠psihar.net Oct. 27, 2002

Oct. 27, 2002

test

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Linking problems with msvc+stlport
by Nicodemus Oct. 26, 2002

Oct. 26, 2002

Hail! I've been trying to use boost python with the msvc 6.0 compiler and STLport-4.5.3 for two weeks now, without success. I've read the tutorial, and created a short snippet to export a simple class that represents color information. I compiled boost without problems (using the "msvc-stlport" toolset), and I'm using Python 2.2 (ActiveState's distribution). I'm using a msvc project to build a DLL, and during the linking stage it complains about the following unresolved externals: void boost::python::objects::register_dynamic_id_aux(...) class boost::python::api::object __cdecl boost::python::objects::function_object Plus, it gives some warnings about: "non dll-interface class 'boost::noncopyable' used as base for dll-interface struct 'boost::python::instance_holder'" I've also done the same tests using the Intel 6.0 compiler, and it gives the same unresolved externals, but no warnings. I didn't compile boost with Intel and STLport support because I couldn't find in the documentation a tool to do it, but would like to do it, since I don't plan to use the msvc compiler, which was used just for the sake of this tests. I plan also to create a static library for embedding purposes, so that I can link this library with a program, and use the objects exported by it. To do this, I compile the lib with the flag BOOST_PYTHON_STATIC_LIB, and it gives 2 warnings (about int being cast to bool), and in the main() of the program I call the function initmymodule() (there's a better way to do this?). When I try to compile my application thought, it gives the same unresolved externals above. On the other hand, If I don't use STLport (including compiling boost with the "msvc" toolset), everything works as expected, both the DLL and the embeded application. What can I do to successfuly compile both the application and the DLL? Any pointer will be great! Thanks a lot, Nicodemus.

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type convert: python file <-> C++ FILE*
by Liwei Peng Oct. 26, 2002

Oct. 26, 2002

Hi, I am using Boost Python V2 to wrap my C++ code. I failed to convert python file to/from C++ FILE*. Here is my code: ---------------------------------------- struct FILE_to_pyfile { static PyObject* convert(FILE* x) { return PyFile_FromFile(x, "", "", NULL); } }; FILE* getfile(const char* fname) { printf("openning file: %s\n", fname); FILE* f = fopen(fname, "w"); fprintf(f, "initial words\n"); return f; } BOOST_PYTHON_MODULE(numbermod) { python::to_python_converter<FILE*, FILE_to_pyfile>(); python::def("getfile", getfile, python::return_internal_reference<>()); } ----------------------------------------------- After I compiled the code, in python run f = getfile("hello.txt") gave me the following error: Traceback (most recent call last): File "./test.py", line 18, in ? f1 = getfile("hello.txt") TypeError: bad argument type for built-in operation Can you kindly tell me 1) what's wrong with the above code? 2) The above code is from C++ 'FILE*' to python file. If I want to convert python file to C++ file, how can I do that? Thanks in advance. Liwei

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