Mailman 3 August 2006 - Cplusplus-sig

Writing configure checks for libboost?
by Hans Meine Aug. 28, 2006

Aug. 28, 2006

Hi! Does anyone have a useful configure check for the boost::python dynamic library (under Unix)? Since Boost encodes build information, not only threading/debug status, but also toolset and library version into the filename, it seems to be rather hard to find reliably. It appears sensible to link the specific filename to a generic one like "libboost_python.so*", as we did locally and several Linux distributions do too, but they differ in the chosen filenames as a quick survey shows: Debian testing (http://ftp.debian.org/debian/pool/main/b/boost/) installs into /usr/lib: *libboost_python-gcc-1_33_1.so.1.33.1 *libboost_python-gcc-mt-1_33_1.so.1.33.1 and obviously links via the "shlibs" file: libboost_python-gcc-1_33_1 1.33.1 libboost-python1.33.1 libboost_python-gcc-mt-1_33_1 1.33.1 libboost-python1.33.1 Also, Ubuntu Breezy (http://packages.ubuntulinux.org/cgi-bin/search_contents.pl?searchmode=filel…) installs the following: *libboost_python-gcc-mt-1_33.so.1.33.0 (There are no links listed, but that could be a shortcoming of the listing.) SuSE 10.1 boost-1.33.1-17.pm.2.i586.rpm installs into /usr/lib: @libboost_python-gcc-1_33.so.1.33.0 @libboost_python-gcc-1_33_1.so.1.33.1 *libboost_python.so.1.33.1 (Note that the regular file has the short name, and the links contain the toolset name.) Fedora Core 3 (http://rpmfind.net/linux/RPM/fedora/updates/testing/3/x86_64/boost-1.33.0-3…) installs into /usr/lib only: *libboost_python.so.1.33.0 (Yes, I may have overlooked some tricks in the installation procedures, since I only looked at the package contents.) -- Ciao, / / /--/ / / ANS

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A question about PyImport_AppendInittab
by Qun Cao Aug. 26, 2006

Aug. 26, 2006

Hi Everyone, I am adopting the code in boost/libs/python/test/embedding.cpp for my project. Here is my question, in embedding.cpp we have: if (PyImport_AppendInittab("embedded_hello", initembedded_hello) == -1) throw std::runtime_error("Failed to add embedded_hello to the interpreter's " "builtin modules"); I noticed #define BOOST_PYTHON_MODULE BOOST_PYTHON_MODULE_INIT in module.hpp file, so I guess "initembedded_hello" here is a pointer to the module "embedd_hello". However, in my project, BOOST_PYTHON_MODULE{} definition code sits in a different class class_wrapper.cpp than main.cpp, does that mean i need to include class_wrapper.cpp in main.cpp? That gives me wierd problem in compilation though. Also, generally, why main.cpp needs to know how a C++ wrapper module is created? Isn't it enough to tell it that there exists a python module in class.dll and the embedded python interpreter will just understand everything from there? Thanks for any insights, Qun

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how to convert C++ objects into python objects?
by Qun Cao Aug. 25, 2006

Aug. 25, 2006

Hi Everyone, I have a question regarding type conversion when embedding python in C++. First, I have created a python module of an C++ class using boost, #include <classA.cpp> BOOST_PYTHON_MODULE(PythonTest) { class_<classA>("classA", init<MyString, MyString, MyPoint3>()); } MyString, MyPoint3 are class types defined in the C++ libraries. It compiles and generate PythonTest.dll. Now, I want to call some Python code (object =classA(MyString, MyString, MyPoint3) from my main.cpp to create a classA object, how do I convert MyString, MyPoint3 variables into Python types? Also since the python module does not know anything about C++ objects MyString, MyPoint3; is it necessary to extending those classes into Python? I saw some ways of convert native types such as int, string in C/Python API, but nothing about generic type conversions. Thanks for your help! Qun

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Problems with Boost Python scope and -fno-elide-constructors
by Martin Reddy Aug. 25, 2006

Aug. 25, 2006

Hi there, We recently came across an interesting problem where boost scopes do not appear to be closed correctly when the code is compiled with the -fno-elide-constructors gcc option. We have worked around this with a small modification to the boost/python/scope.hpp. For example, take the following simple example: void wrapScope1() { scope errorScope = class_<Scope1, Scope1*, boost::noncopyable> ( "Scope1", "", no_init ) .def("sayHello", &SayHello); } void wrapScope2() { class_<Scope2, Scope2*, boost::noncopyable> ( "Scope2", "", no_init ) .def("sayHello", &SayHello); } BOOST_PYTHON_MODULE( MyModule ) { wrapScope1(); wrapScope2(); } When compiled normally you get Scope1 and Scope2 at the same level, as you would expect. However, if you compile this code with -fno-elide-constructors (which we do to workaround gcov bugs) then Scope2 is nested inside of Scope1. The problem is that -fno-elide-constructors causes 2 scope objects to get created: an initial temporary scope object is created, and then the copy constructor is called to copy this into the errorScope variable. The temporary scope is then immediately destroyed (popping the scope to the previous value), and then at the end of wrapScope1() errorScope is destroyed, popping the scope to the value of the temporary scope. To work around this, I made a small fix to scope.hpp to replace the m_previous_scope pointer with a vector that forms a stack of scope pointers. There may be more elegant fixes to this problem that this group may want to consider, but I figured I'd pass along the one potential change that works well for us. I have put a complete repro case, along with the code changes that I made to address this, and a diff -c patch file, into a tarball at: http://www.martinreddy.net/tmp/boost-scope.tgz (This problem occurred for us under gcc 4.0.x, boost 1.33.1, under Fedora Core.) Cheers, Martin. --------------------------------------------------------------------------- Martin Reddy Pixar Animation Studios 1200 Park Avenue reddy(a)pixar.com Emeryville, CA 94608 http://MartinReddy.net/ Tel. (510) 752 4093

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Embedding Python into a Shared Object
by bEngO Aug. 24, 2006

Aug. 24, 2006

Dear all, I am trying to embed Python into an application through a plug-in ( dynamically loaded shared object ). And I do not know how I should link with Python when building my plug-in. The plugin ( embedded Python interpreter ) works until I try to import a module. Import failed because some symbols ( like _Py_NoneStruct ) are undefined. The Python doc ( http://docs.python.org/ext/link-reqs.html ) says I should use the flags given by: >>> import distutils.sysconfig >>> distutils.sysconfig.get_config_var('LINKFORSHARED') Which are ( i am using GNU GCC 4.1.0 on Linux ): '-Xlinker -export-dynamic' ( I also tried -rdynamic and -Wl,-E which should be equivalent ) But this is doing nothing for me. Is it because this linker flag is only relevant when building an executable, and do nothing when building a shared object ? Or is it a bug of GCC 4.1.0 ? Or is it because I link against libpythonX.X.so instead of libpythonX.X.a ? But I think I shouldn't link against libpythonX.X.a since it isn't Position Independent Code ( GCC -fpic flag ) which is required when building a shared object... Please help :) I searched the web and found people being stuck on the same problem but no workaround... Thanks in advance. bEngo

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Boost Python private members problem
by Eduardo Picado Aug. 24, 2006

Aug. 24, 2006

Hi, I'm facing a problem with the last module I need to compile with Boost Python. I receive this compilation error: Compiling...(with vc-8_0) TASRLogger.cpp C:\Python24\include\TASRLogger.hpp(353) : error C2248: 'TASRLogger::TASRLogger' : cannot access private member declared in class 'TASRLogger' C:\Python24\include\TASRLogger.hpp(37) : see declaration of 'TASRLogger::TASRLogger' C:\Python24\include\TASRLogger.hpp(33) : see declaration of 'TASRLogger' This diagnostic occurred in the compiler generated function 'TASRDefaultLogger::TASRDefaultLogger(const TASRDefaultLogger &)' It's hard find a solution for the problem as I don't have the sources for the dll. Otherwise I could at least change the member attributes visibility. Is there a workaround for it? I tried to extract the relevant parts from the files. The TASRLogger.hpp I'm trying to wrap: class TASRLoggerInternal; class TASRDefaultLoggerInternal; struct GrammarsInternal; /** * Base virtual class for session loggers. * The TASRLogger specifies all methods a session logger should implement. */ class TASRLogger { TASRLoggerInternal * _logger; TASRLogger(TASRLogger const &); public: TASRLogger() throw (std::bad_alloc); virtual ~TASRLogger(); }; /** * Default implementation for simple session loggers. */ class TASRDefaultLogger : public TASRLogger { TASRDefaultLoggerInternal * data; TASRDefaultLogger(TASRDefaultLogger const &); public: TASRDefaultLogger(size_t diskMinFreeSize = 10000, bool hierarchical = true, TASRString const & root = "") throw (std::bad_alloc, TASRDirectoryAccessError); ~TASRDefaultLogger(); }; The TASRLogger.cpp: // Boost Includes ============================================================== #include <boost/python.hpp> #include <boost/cstdint.hpp> // Includes ==================================================================== #include <TASRLogger.hpp> // Using ======================================================================= using namespace boost::python; // Declarations ================================================================ namespace { struct TASRLogger_Wrapper: TASRLogger { TASRLogger_Wrapper(PyObject* py_self_): TASRLogger(), py_self(py_self_) {} PyObject* py_self; }; struct TASRDefaultLogger_Wrapper: TASRDefaultLogger { TASRDefaultLogger_Wrapper(PyObject* py_self_, const TASRDefaultLogger& p0): TASRDefaultLogger(p0), py_self(py_self_) {} TASRDefaultLogger_Wrapper(PyObject* py_self_): TASRDefaultLogger(), py_self(py_self_) {} TASRDefaultLogger_Wrapper(PyObject* py_self_, size_t p0): TASRDefaultLogger(p0), py_self(py_self_) {} TASRDefaultLogger_Wrapper(PyObject* py_self_, size_t p0, bool p1): TASRDefaultLogger(p0, p1), py_self(py_self_) {} TASRDefaultLogger_Wrapper(PyObject* py_self_, size_t p0, bool p1, const TASRString& p2): TASRDefaultLogger(p0, p1, p2), py_self(py_self_) {} PyObject* py_self; }; }// namespace // Module ====================================================================== BOOST_PYTHON_MODULE(TASRLogger) { scope* TASRLogger_scope = new scope( class_< TASRLogger, boost::noncopyable, TASRLogger_Wrapper >("TASRLogger", init< >()) ); delete TASRLogger_scope; class_< TASRDefaultLogger, bases< TASRLogger > , TASRDefaultLogger_Wrapper >("TASRDefaultLogger", init< const TASRDefaultLogger& >()) .def(init< optional< size_t, bool, const TASRString& > >()) ; } Thanks, Eduardo Picado -- Eduardo PICADO MSN eduardo.picado(a)gmail.com portable +33 6 32 47 10 10 (NEW) fix +33 1 45 03 52 54 |̲̅<̲̅Θ̲̅>̲̅|

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debug a python extension
by michael_gruner＠arcor.de Aug. 23, 2006

Aug. 23, 2006

Hello, I have a binary dll file (compiled for debugging) which I built a wrapper for with boost.python. Within this binary there exists a derived class which destructor seems to have a problem. If I instantiate the class and del it afterwards Python crashes. Do you have any advices how I may debug this within msvc or any other windows debugger? Thanks for your help. Michael

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Under what conditions would PyRun_SimpleFile return false?
by Blake Skinner Aug. 22, 2006

Aug. 22, 2006

PyRun_SimpleFile() doesn't seem to like me. First, passing a FILE* created by fopen() in Visual Studio 2005 caused a runtime error, but I found a work around: FILE* fp = PyFile_AsFile( PyFile_FromString(filename, "r") ); PyRun_SimpleString(fp, filename); I'm mentioning this so you understand why I'm doing it in my code. This worked fine, until I tried to construct a class around boost python, here's the jist of it: // constructor, Initializes python, creates the main module and gets the // dictionary pyEngine::pyEngine() { Py_Initialize(); // main module and main dictionary object main(( handle<>(borrowed(PyImport_AddModule("__main__"))) )); _main = main; _mdict = _main.attr("__dict__"); } // destructor // finalizes python pyEngine::~pyEngine() { Py_Finalize(); } ////////////////////////////////////////////////////////////////// // methods // load a python module with the given filename bool pyEngine::LoadModule(char *filename) { // originally more condensed, the 'if's were added for debugging PyObject *py_file = PyFile_FromString(filename, "r"); if (!py_file) { fprintf(stderr, "Unable to locate module (pyEngine)\n"); return false; } FILE *fp = PyFile_AsFile( py_file ); if (!fp) { fprintf(stderr, "PyFile_AsFile returned NULL\n"); return false; } if (!(PyRun_SimpleFile(fp, filename) == 1)) { fprintf(stderr, "PyRun_SimpleFile returned 0\n"); return false; } return true; } /////////////////////////////////////////////////////////////////////////////// >From stderr I found that PyRun_SimpleFile was returning 0. I checked the documentation and it didn't mention what conditions that would happen for. I'll keep looking for it on my own and post if I solve it, but any help would be appreciated. Thanks.

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Modules using Boost Python are giving “error LNK2019: unresolved external symbol”
by Eduardo Picado Aug. 17, 2006

Aug. 17, 2006

Hi, Some modules of the application I'm trying to build with Boost Python are giving the same problem, for example: # Jamfile: project-root ; import python ; extension TASRRecognitionControl : TASRRecognitionControl.cpp # requirements and dependencies for Boost.Python extensions <template>@boost/libs/python/build/extension : # additional requirements <library-file>../telisma/lib/libtasr_so.lib ; # TASRRecognitionControl.hpp (only showing relevant parts) struct TASRRecognitionControlInternal; class TASRRecognitionControl { private: TASRRecognitionControlInternal * _ctrl; friend class TASREngineInternal; public: TASRRecognitionControl(TASRRecognitionControlInternal * ctrl); public: TASRRecognitionControl(); TASRRecognitionControl(TASRRecognitionControl const & recoctrl); ~TASRRecognitionControl(); # TASRRecognitionControl.cpp (only showing relevant parts) BOOST_PYTHON_MODULE(TASRRecognitionControl) { class_< TASRRecognitionControl >("TASRRecognitionControl", init< >()) .def(init< TASRRecognitionControlInternal* >()) // HERE is the problem .def(init< const TASRRecognitionControl& >()) ; } Compiling: C:\boost_1_33_1\libs\python\example\telismaPyste>bjam -sTOOLS=vc-8_0 ...found 1624 targets... ...updating 4 targets... vc-C++ bin\telismaPyste\TASRRecognitionControl.pyd\vc-8_0\debug\threading-multi\TASRRecognitionControl.obj TASRRecognitionControl.cpp vc-Link bin\telismaPyste\TASRRecognitionControl.pyd\vc-8_0\debug\threading-multi\TASRRecognitionControl.pyd bin\telismaPyste\ TASRRecognitionControl.pyd\vc-8_0\debug\threading-multi\TASRRecognitionControl.lib Creating library bin\telismaPyste\TASRRecognitionControl.pyd\vc-8_0\debug\threading-multi\TASRRecognitionControl.lib and o bject bin\telismaPyste\TASRRecognitionControl.pyd\vc-8_0\debug\threading-multi\TASRRecognitionControl.exp TASRRecognitionControl.obj : error LNK2019: unresolved external symbol "public: __thiscall TASRRecognitionControl::TASRRecogn itionControl(struct TASRRecognitionControlInternal *)" (??0TASRRecognitionControl@@QAE@PAUTASRRecognitionControlInternal@@@Z) referenced in function "public: __thiscall boost::python::objects::value_holder<class TASRRecognitionControl>::value_holder< class TASRRecognitionControl><struct TASRRecognitionControlInternal *>(struct _object *,struct TASRRecognitionControlInternal *)" (??$?0PAUTASRRecognitionControlInternal@@@?$value_holder@VTASRRecognitionControl@@@objects@python@boost@@QAE@PAU_object@ @PAUTASRRecognitionControlInternal@@@Z) bin\telismaPyste\TASRRecognitionControl.pyd\vc-8_0\debug\threading-multi\TASRRecognitionControl.pyd : fatal error LNK1120: 1 unresolved externals Microsoft (R) Manifest Tool version 5.2.3790.2014 Copyright (c) Microsoft Corporation 2005. All rights reserved. mt.exe : general error c10100b1: Failed to load file "bin\telismaPyste\TASRRecognitionControl.pyd\vc-8_0\debug\threading-mult i\TASRRecognitionControl.pyd". Le fichier spicifii est introuvable. CALL "C:\Program Files\Microsoft Visual Studio 8\Common7\Tools\..\..\VC\bin\vcvars32.BAT" >nul "C:\Program Files\Microsoft Visual Studio 8\Common7\Tools\..\..\VC\bin\link" /nologo /INCREMENTAL:NO /DEBUG /DLL /subsyst em:console /out:"bin\telismaPyste\TASRRecognitionControl.pyd\vc-8_0\debug\threading-multi\TASRRecognitionControl.pyd" /IMPLI B:"bin\telismaPyste\TASRRecognitionControl.pyd\vc-8_0\debug\threading-multi\TASRRecognitionControl.lib" /LIBPATH:"c:\Python24 \libs" /LIBPATH:"bin\boost\libs\python\build\boost_python.dll\vc-8_0\debug\threading-multi" "python24.lib" "boost_python.lib " @"bin\telismaPyste\TASRRecognitionControl.pyd\vc-8_0\debug\threading-multi\TASRRecognitionControl.CMD" mt -manifest bin\telismaPyste\TASRRecognitionControl.pyd\vc-8_0\debug\threading-multi\TASRRecognitionControl.pyd.manifest -outputresource:bin\telismaPyste\TASRRecognitionControl.pyd\vc-8_0\debug\threading-multi\TASRRecognitionControl.pyd;#2 ...failed vc-Link bin\telismaPyste\TASRRecognitionControl.pyd\vc-8_0\debug\threading-multi\TASRRecognitionControl.pyd bin\tel ismaPyste\TASRRecognitionControl.pyd\vc-8_0\debug\threading-multi\TASRRecognitionControl.lib... ...failed updating 2 targets... ...updated 2 targets... So, I don't know how to export the constructor .def(init< TASRRecognitionControlInternal* >()) that uses the class TASRRecognitionControlInternal that is declared but not defined in my header. Thanks very much, Eduardo Picado -- Eduardo PICADO MSN eduardo.picado(a)gmail.com portable +33 6 32 47 10 10 (NEW) fix +33 1 45 03 52 54 |̲̅<̲̅Θ̲̅>̲̅|

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ImportError: timemodule.so
by RICH JOHNSON Aug. 15, 2006

Aug. 15, 2006

I am new to boost python and am having difficulty importing python modules into a little C++ program. Any insight into the problem would be appreciated. OS: Linux Redhat gcc: 3.2.3 python 2.2 boost 1.33.1 >From the command line I can do: [rjohnson@pitwar7 rjohnson]$ python Python 2.2.3 (#1, Feb 15 2005, 02:41:06) [GCC 3.2.3 20030502 (Red Hat Linux 3.2.3-49)] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>>from time import time,ctime >>>print 'Today is', ctime(time()) Today is Fri Aug 4 10:47:20 2006 >>> But the C++ program below outputs: 25 20 Traceback (most recent call last): File "<string>", line 1, in ? ImportError: /usr/lib/python2.2/lib-dynload/timemodule.so: undefined symbol: PyDict_SetItemString #include <boost/python.hpp> #include <iostream> int main(int, char **) { using namespace boost::python; Py_Initialize(); try { PyRun_SimpleString("result = 5 ** 2"); object module((handle<>(borrowed(PyImport_AddModule("__main__"))))); object dictionary = module.attr("__dict__"); object result = dictionary["result"]; int result_value = extract<int>(result); std::cout << result_value << std::endl; dictionary["result"] = 20; PyRun_SimpleString("print result"); // Here is the same command that ran successfully at the command line above but fails from C++ PyRun_SimpleString("from time import time,ctime\n" "print 'Today is',ctime(time())\n"); } catch (error_already_set) { PyErr_Print(); } Py_Finalize(); return 0; } My LD_LIBRARY_PATH is /usr/local/lib:/usr/lib/python2.2/config PYTHONPATH is /usr/lib/python2.2/config

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