[C++-sig] Boost.Python and lifetime of instances of C++ classes

[David Abrahams]

----- Original Message -----
From: "Hugo van der Merwe" <s13361562 at bach.sun.ac.za>

> True, I didn't bother to have data members, etc. But anyway, that is
> irrelevant. The question is how can I go about "solving" this? (I
> mentioned this in a previous thread, but without the code it was
> probably not clear what I meant.)

include <iostream.h>
include <boost/smart_ptr.hpp>

class test {
public:
    test() { std::cout << "test Constructor called." << std::endl; }
    ~test() { std::cout << "test Destructor called." << std::endl; }
    void print() { std::cout << "HELLO!" << std::endl; }
    static boost::shared_ptr<test> create() {
        return boost::shared_ptr<test>(new test);
    }
};

class foo {
public:
    void add(boost::shared_ptr<test> t) { sav = t; }
    void print() { sav->print(); }
private:
    boost::shared_ptr<test> sav;
};

#include <boost/python/class_builder.hpp>

BOOST_PYTHON_MODULE_INIT(test)
{
    boost::python::module_builder this_module("test");

    boost::python::class_builder<test> test_class(this_module, "test");
    this_module.def(&test::create, "testclass");
    test_class.def(&test::print, "printit");

    boost::python::class_builder<foo> foo_class(this_module, "foo");
    foo_class.def(boost::python::constructor<>());
    foo_class.def(&foo::add, "add");
    foo_class.def(&foo::print, "printit");
}

...or you can wait for Boost.Python V2, coming soon, which will handle this
problem much better.