#include <boost/python.hpp>

#include <memory>

#include <iostream>

using namespace boost::python;

struct Foo {

Foo(int v) : value(v) { std::cout << "Foo(" << value << ") constructed\n"; }

~Foo() { std::cout << "Foo(" << value << ") destroyed\n"; }

void hello() const { std::cout << "Hello from Foo(" << value << ")\n"; }

int value;

};

// --- 1. Owned instance (Python owns) ---

std::shared_ptr<Foo> make_owned(int v) {

return std::make_shared<Foo>(v);

}

// --- 2. Borrowed instance (C++ owns) ---

Foo globalFoo(999);

Foo* get_borrowed() {

return &globalFoo; // still alive for entire program

}

BOOST_PYTHON_MODULE(example)

{

class_<Foo, std::shared_ptr<Foo>>("Foo", init<int>())

.def("hello", &Foo::hello)

.def_readwrite("value", &Foo::value);

// Python owns this one

def("make_owned", &make_owned);

// Python borrows this one (C++ owns it)

def("get_borrowed", &get_borrowed,

return_value_policy<reference_existing_object>());

}