From alain.miniussi at oca.eu  Thu Jun 11 09:28:44 2020
From: alain.miniussi at oca.eu (Alain O' Miniussi)
Date: Thu, 11 Jun 2020 15:28:44 +0200 (CEST)
Subject: [C++-sig] Boost class to represent PyBytesObject ?
Message-ID: <194917008.490962.1591882124641.JavaMail.zimbra@oca.eu>


Hi,

The pickle API has changed between Python 2 and 3, moving from str (represented by the boost::python::str class) to bytes.
For serialization purpose, I need to represent the Python's bytes (PyBytesObject in C) type in C++. 
What would be the the best type to extract<waht?> to ?

Thank
  
----
Alain Miniussi
DSI, P?les Calcul et Genie Log.
Observatoire de la C?te d'Azur
T?l. : +33492003009 (Mont-Gros)
       +33483618544 (Sophia Antipolis)
       +33609650665

From dcirmirakis at gmail.com  Wed Jun 24 05:45:58 2020
From: dcirmirakis at gmail.com (Dominik Cirmirakis)
Date: Wed, 24 Jun 2020 10:45:58 +0100
Subject: [C++-sig] Boost Python issue with converters - static linking
Message-ID: <da369267-be5b-cda0-5aca-2bbe27fdcec9@gmail.com>

Hi,

I have a question regarding the below code.

It's an example how to pass a custom class via shared_ptr to embedded 
python code and it works when boost is dynamically linked.

Unfortunately the same code with statically linked boost doesn't work 
with the following error message:

"No to_python (by-value) converter found for C++ type: class 
boost::shared_ptr<class Foo>".

I don't understand why a different linking can affect type recognition 
of a registered converter. What am I missing?

Can anybody help me out?

Thanks,

Dominik


https://stackoverflow.com/questions/8225934/exposing-a-c-class-instance-to-a-python-embedded-interpreter?noredirect=1&lq=1


#include <boost/shared_ptr.hpp>
#include <boost/make_shared.hpp>
#include <boost/python.hpp>
#include <string>
#include <iostream>

namespace bp = boost::python;

struct Foo{
 ??? Foo(){}
 ??? Foo(std::string const& s) : m_string(s){}
 ??? void doSomething() {
 ??????? std::cout << "Foo:" << m_string << std::endl;
 ??? }
 ??? std::string m_string;
};

typedef boost::shared_ptr<Foo> foo_ptr;

BOOST_PYTHON_MODULE(hello)
{
 ??? bp::class_<Foo, foo_ptr>("Foo")
 ??????? .def("doSomething", &Foo::doSomething)
 ??? ;
};

int main(int argc, char **argv)
{
 ??? Py_Initialize();
 ??? try {
 ??????? PyRun_SimpleString(
 ??????????? "a_foo = None\n"
 ??????????? "\n"
 ??????????? "def setup(a_foo_from_cxx):\n"
 ??????????? "??? print 'setup called with', a_foo_from_cxx\n"
 ??????????? "??? global a_foo\n"
 ??????????? "??? a_foo = a_foo_from_cxx\n"
 ??????????? "\n"
 ??????????? "def run():\n"
 ??????????? "??? a_foo.doSomething()\n"
 ??????????? "\n"
 ??????????? "print 'main module loaded'\n"
 ??????? );

 ??????? foo_ptr a_cxx_foo = boost::make_shared<Foo>("c++");

 ??????? inithello();
 ??????? bp::object main = bp::object(bp::handle<>(bp::borrowed(
 ??????????? PyImport_AddModule("__main__")
 ??????? )));

 ??????? // pass the reference to a_cxx_foo into python:
 ??????? bp::object setup_func = main.attr("setup");
 ??????? setup_func(a_cxx_foo);

 ??????? // now run the python 'main' function
 ??????? bp::object run_func = main.attr("run");
 ??????? run_func();
 ??? }
 ??? catch (bp::error_already_set) {
 ??????? PyErr_Print();
 ??? }

 ??? Py_Finalize();

 ??? return 0;
}