Mailman 3 December 2012 - Cplusplus-sig

boost::python embedding error - runtime - Mac OS X - 1.38
by Igor Karpov Oct. 1, 2014

Oct. 1, 2014

Hi, I am trying to run the following program: #include <iostream> #include <Python.h> #include <boost/python.hpp> using namespace boost::python; using namespace std; int main(int argc, char** argv) { { // Using Python/C Py_Initialize(); PyObject* main_module = PyImport_ImportModule("__main__"); PyObject* globals = PyEval_GetGlobals(); PyObject* locals = PyEval_GetLocals(); PyRun_SimpleString("print 'Hello World, from Python/C!'\n"); Py_Finalize(); } { // Using boost::python Py_Initialize(); object main_module = import("__main__"); object main_namespace = main_module.attr("__dict__"); try { object ignored = exec("print 'Hello World, from boost::python!'\n", main_namespace); Py_Finalize(); } catch (error_already_set const& e) { PyErr_Print(); return 1; } } return 0; } on Linux (both x86 and x86_64), with Ubuntu's default version of Boost (1.34.1) installed, I am able to do so as expected: $ ./embed Hello World, from Python/C! Hello World, from boost::python! on Mac OS X, I get a runtime error: $ ./embed Hello World, from Python/C! Bus Error Running with gdb, this is the stack trace: Hello World, from Python/C! Program received signal EXC_BAD_ACCESS, Could not access memory. Reason: KERN_PROTECTION_FAILURE at address: 0x00000000 0x00000000 in ?? () (gdb) where #0 0x00000000 in ?? () #1 0x00bb618f in PyEval_GetGlobals () #2 0x00bce0dd in PyImport_Import () #3 0x00bce2b0 in PyImport_ImportModule () #4 0x008127d4 in boost::python::import (name=@0xbffff4a8) at libs/python/src/import.cpp:20 #5 0x00004446 in main (argc=1, argv=0xbffff510) at embed.cc:22 For this Mac, boost version is latest (1.38) and python version is: Python 2.5.4 (r254:67917, Dec 23 2008, 14:57:27) [GCC 4.0.1 (Apple Computer, Inc. build 5363)] on darwin Is this a bug? I attached the source and the cmake file I am using to build, for convenience. Thanks, --Igor.

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sendkeys method
by sam Sept. 30, 2013

Sept. 30, 2013

Hello, Is there away(method) in C/C++ programming that make the software think that someone pressed the OK button, similar to sendkeys in VBS (WshShell.SendKeys ("{Enter}")) Thank you, Sam

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compile some code with boost.python by mingw in win7-64bit
by simon zhang Jan. 4, 2013

Jan. 4, 2013

I decided to make my program compatible with windows environment.But I have very little programming experience on windows.There are some errors need help. Environment: - os: win7-64bit, - ide: codeblocks12.11, - python: Python 2.7.3 Windows X86-64 Installer (Windows AMD64 / Intel 64 / X86-64 binary [1] -- does not include source) - compiler: mingw that come from codeblocks installation package. - boost: boost1.52 I only copy and test this "hello" code that come from ".\boost_1_52_0\libs\python\example\tutorial" Code: #include <iostream>#include <boost/python/module.hpp>#include <boost/python/def.hpp> char const* greet(){ return "hello, world"; } BOOST_PYTHON_MODULE(hello_ext){ using namespace boost::python; def("greet", greet);} using namespace std;int main(){ cout << "Hello world!" << endl; return 0;} Error info: mingw32-g++.exe -Wall -fexceptions -g -ID:\boost\include\boost-1_52 -IC:\Python27\include -c E:\project\snail-MW\test1\main.cpp -o obj\Debug\main.o mingw32-g++.exe -LD:\boost\lib\ -LC:\Python27\libs -o bin\Debug\test1.exe obj\Debug\main.o -static obj\Debug\main.o: In function `inithello_ext': E:/project/snail-MW/test1/main.cpp:11: undefined reference to `boost::python::detail::init_module(char const*, void (*)())' obj\Debug\main.o: In function `ZNK5boost6python9type_info4nameEv': D:/boost/include/boost-1_52/boost/python/type_id.hpp:165: undefined reference to `boost::python::detail::gcc_demangle(char const*)' obj\Debug\main.o: In function `ZNK5boost6python15to_python_valueIRKPKcEclES5_': D:/boost/include/boost-1_52/boost/python/converter/builtin_converters.hpp:161: undefined reference to `boost::python::converter::do_return_to_python(char const*)' ................ It have also do some errors that only compile by the command of "bjam toolset=gcc variant=release " in the station ".\boost_1_52_0\libs\python\example\tutorial".

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RAII for the GIL in Boost.Python?
by John Zwinck Jan. 1, 2013

Jan. 1, 2013

I posted this to the Boost list, where it was suggested this list as a next step. If you saw it there, the rest of this message is the same. There are many questions and example classes online for dealing with Python's Global Interpreter Lock (GIL) using RAII. I think Boost.Python should provide this functionality, rather than having users who build hybrid C++/Python applications copy-pasting code from various places. I was one of those users recently, and the code I developed to deal with it is now public: https://github.com/jzwinck/pccl/blob/master/InterpreterLockGuard.hpp https://github.com/jzwinck/pccl/blob/master/InterpreterLockGuard.cpp https://github.com/jzwinck/pccl/blob/master/test/InterpreterLockGuard.test.… Comments in the header explain how to use it in the context of Boost.Python, and contain a link to a wiki from which some of the code was originally copied. Why add this to Boost? It's clearly code that a bunch of people need, often people who are already using Boost.Python. It has a permissive license, and I can re-license it if need be. And it depends on Boost (mostly for thread-specific storage--I hope this dependency won't be seen as a liability here, though it could be removed if needed). This particular implementation was used successfully in a few programs in a commercial setting on Fedora and RHEL systems. It has some extra checks that we found helpful compared to some of the versions you'll find posted online. The code also builds and passes its tests with GCC on Mac OS X. I welcome any feedback regarding the suitability for inclusion in Boost of this particular code and/or the concepts it implements. John Zwinck

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How to converter std::string* in boost.python?
by simon zhang Dec. 25, 2012

Dec. 25, 2012

How to converter std::string* in boost.python?I have to handle some data of c++ in python.The data may be big.So I return a pointer to python. But there are some errors. c++ #include <boost/python.hpp>#include <string> class A {public: A() { data="342342fgsf"; ss=&data; } std::string *ss; std::string data;}; BOOST_PYTHON_MODULE(ctopy){ using namespace boost::python; class_<A> ("A",init<>()) .add_property(ss,&A::ss) ;} python import ctopy t1=ctopy.A() print t1.ss #error.TypeError:No to_python (by-value) converter found for c++ type:std::string*

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Why can't kill process by Ctrl-c in a boost.python module with an endless loop
by simon zhang Dec. 24, 2012

Dec. 24, 2012

I have make a boost.python module with an endless loop.But I can't kill the process by ctrl-c.The following is an example. C++ #include <boost/python.hpp>#include <boost/python.module.hpp>#include <boost/python.def.hpp>#include <iostream> usring namespace boost::python; void foo() { int it=0; while (true) { //endless loop ++it; std::cout<< it <<std::endl; sleep(3); }} BOOST_PYTHON_MODULE(ctopy){ def("foo",foo);} python: import ctopy ctopy.foo() result: 1234..................... I can't kill the foreground process by Ctrl-c.why the module don't accept signal "SIGINT" that was sent by Ctrl-c.How to make it work.

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Trouble destructor, call python's object with pointer in boost.python
by simon zhang Dec. 22, 2012

Dec. 22, 2012

when I call python's function with pointer as an argument in boost.python, there are some troubles in destructor. The following is a sample code #include <boost/python.hpp>#include <boost/python/module.hpp>#include <boost/python/def.hpp>#include <string>#include <iostream>using namespace boost::python; class A {public: A() { std::cout<< "A start"<<std::endl; } ~A() {std::cout<< "A end" <<std::endl;}}class B {public: B() { aa=new A; } ~B() { delete aa; } void run(object ct) { _obj=ct(); //creat a python object _obj.attr("fun1")(aa); //call a function named "fun1" with a pointer arg _obj.attr("fun2")(aa); //call a function named "fun2" with a pointer arg } A *aa; object _obj;} BOOST_PYTHON_MODULE(ctopy){ class_<A> ("A",init<>()) ; class_<b> ("B",init<>()) .def("run",&B::run) ;} python: import ctopyclass tc: def fun1(self,tt): print "fun1" def fun2(self,tt): print "fun2" bb=ctopy.D() bb.run(tc) this result: A start fun1 A end fun2 A end A end note: The "A end" has been printed three.I try it in "valgrind"，there are some errors.I just want to run the destructor once.How to do?

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Re: [C++-sig] Adding method at run-time to class instances
by Christophe Tornieri Dec. 21, 2012

Dec. 21, 2012

Here is some code. The main idea is that I don't want to expose each derived module classes but only the interface IModule that contains all the necessary information at run-time. The following code is actually working but produces the following warning: to-Python converter for class ModuleConfiguration already registered; second conversion method ignored This sounds normal as the class is exposed each time a new instance of MyModule or MySecondModule is created. // Dummy class for test class IModule : public Vx::VxInputOutputInterface { public: IModule() {} }; class ModuleConfiguration { public: ModuleConfiguration(IModule& iProxy); IModule& mProxy; }; template<typename T> struct GetParameterFunctor; template<> struct GetParameterFunctor<int> { GetParameterFunctor(const std::string& iName) : mName(iName) { } int operator()(ModuleConfiguration* iProxy) { return iProxy->mProxy.getParameter(mName).getFieldBase().toInteger(); } std::string mName; }; template<typename T> struct SetParameterFunctor { SetParameterFunctor(const std::string& iName) : mName(iName) { } int operator()(ModuleConfiguration* iProxy, T iValue) { return iProxy->mProxy.getParameter(mName).setValue(iValue); } std::string mName; }; namespace boostVx { namespace python { namespace detail { boostVx::mpl::vector<int, ModuleConfiguration*> get_signature(boostVx::function<int (ModuleConfiguration*)>, ModuleConfiguration*) { return boostVx::mpl::vector<int, ModuleConfiguration*>(); } boostVx::mpl::vector<int, ModuleConfiguration*, int> get_signature(boostVx::function<int (ModuleConfiguration*, int)>, ModuleConfiguration*) { return boostVx::mpl::vector<int, ModuleConfiguration*, int>(); } } } } class CreateGetParameterFieldVisitor : public VxData::FieldVisitor { public: CreateGetParameterFieldVisitor(boostVx::python::class_<ModuleConfiguration>& iPythonConfigurationWrapper) : mPythonConfigurationWrapper(iPythonConfigurationWrapper) {} virtual void visit(VxData::Field<int>& i_field) { GetParameterFunctor<int> getP(i_field.getID().asString()); SetParameterFunctor<int> setP(i_field.getID().asString()); mPythonConfigurationWrapper.add_property(i_field.getID().asString(), boostVx::function<int (ModuleConfiguration*)>(getP), boostVx::function<int (ModuleConfiguration*, int)>(setP)); } private: boostVx::python::class_<ModuleConfiguration>& mPythonConfigurationWrapper; }; ModuleConfiguration::ModuleConfiguration(IModule& iProxy) : mProxy(iProxy) { boostVx::python::class_<ModuleConfiguration> pythonConfigurationWrapper("ModuleConfiguration", boostVx::python::no_init); CreateGetParameterFieldVisitor visitor(pythonConfigurationWrapper); const_cast<VxData::Container&>(mProxy.getParameterContainer()).accept(visitor); } class ModuleWrapperInterface { public: ModuleWrapperInterface(IModule* iProxy) : mProxy(iProxy) , mConfiguration(*iProxy) { } ModuleConfiguration& getModuleConfiguration() { return mConfiguration; } private: IModule* mProxy; ModuleConfiguration mConfiguration; }; class MyModule : public IModule { public: MyModule() : mThreshold(5, "threshold", this) , mCeil(10, "ceil", this) { } const char* getClassName() const { return "MyModule"; } private: Vx::VxParameter<int> mThreshold; Vx::VxParameter<int> mCeil; }; class MySecondModule : public IModule { public: MySecondModule() : mTorque(120, "torque", this) { } const char* getClassName() const { return "MySecondModule"; } private: Vx::VxParameter<int> mTorque; }; boostVx::shared_ptr<ModuleWrapperInterface> createModule(const std::string& iName) { if( iName == "first" ) return boostVx::shared_ptr<ModuleWrapperInterface>(new ModuleWrapperInterface(new MyModule()), NullDeleter()); else if( iName == "second" ) return boostVx::shared_ptr<ModuleWrapperInterface>(new ModuleWrapperInterface(new MySecondModule()), NullDeleter()); else { std::cerr << "No module with name " << iName << " found, returning MyModule." << std::endl; return boostVx::shared_ptr<ModuleWrapperInterface>(new ModuleWrapperInterface(new MyModule()), NullDeleter()); } } BOOST_PYTHON_MODULE(Modules) { boostVx::python::class_<ModuleWrapperInterface, boostVx::shared_ptr<ModuleWrapperInterface>, boostVx::noncopyable>("ModuleInterface", boostVx::python::no_init) .def("getParameters", &ModuleWrapperInterface::getModuleConfiguration, boostVx::python::return_internal_reference<>() ); boostVx::python::def("createModule", &createModule); } -- Christophe Tornieri Tech Lead, Software Architect Sub-sea division christophe.tornieri(a)cm-labs.com http://www.vxsim.com/

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Adding method at run-time to class instances
by Christophe Tornieri Dec. 21, 2012

Dec. 21, 2012

Hi, Is-it possible to add methods to a class instance exposed in Python ? I mean at the object level. I have a class that is wrapped through another class. When an instance of this wrapper class is build at run time (through a Python call), I would like to expose some new methods. In my case, the wrapped class contains a list of properties that is filled at construction. For each of this property, I wanted to expose a new property on the wrapper class in python. Christophe -- Christophe Tornieri Tech Lead, Software Architect Sub-sea division christophe.tornieri(a)cm-labs.com http://www.vxsim.com/

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Exposing function at run-time
by Christophe Tornieri Dec. 21, 2012

Dec. 21, 2012

Hi, class Base { } -- Christophe Tornieri Tech Lead, Software Architect Sub-sea division christophe.tornieri(a)cm-labs.com http://www.vxsim.com/

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