dique <chezdique@[...].com>  writes:

>  Hi all,
> 
>  I have several C++ objects (created with C++ code) and
>  I want them to be accessible and manipulatable by an
>  embeded python script. So far I only manage to let the
>  embeded script access a _copy_ of the C++ object.
>  Hence whatever changes done to the C++ object in the
>  python script wouldn't have any effect on the C++
>  object running in C++ code. How do I make the embeded
>  script able to access and manipulate the C++ object
>  directly?
> 
>  I hope the code below would demonstrate what I mean.
> 
>  #include <string>
>  #include <iostream>
>  #include <boost/python.hpp>
> 
>  using namespace boost::python;
[snip]
>      // This works nicely. But only limited to objects
>  created by Python.
>      object testClass = class_<Test>("Test",
>  init<int>())
>          .def("add", &Test::add);
>      object testObject = testClass(10);
>      pythonScript.addNamedObject("test", testObject);
>      Test& test = extract<Test&>(testObject)();
>      std::cout << "C++: " << test.add(10) << std::endl;
>      pythonScript.run("print 'Python:',
>  test.add(10)\n");
>      std::cout << "C++: " << test.add(10) << std::endl;
> 
>      // Below doesn't work as expected,
>      // as Python and C++ maintain separate copies of test1.
>      Test test1(10);
>      object testObject1(test1);
>      pythonScript.addNamedObject("test1", testObject1);
>      std::cout << "C++: " << test1.add(10) <<
>  std::endl;
>      pythonScript.run("print 'Python:',
>  test1.add(10)\n");
>      std::cout << "C++: " << test1.add(10) <<
>  std::endl;

You could probably get what you want using boost::shared_ptr as the
"HeldType" for use in the Python object. Basically, the problem is
that you want to embed a reference of some sort to the C++ object
within the Python object. This is dangerous unless you have some way
of linking the lifetime of the C++ object to that of the Python object
that references it. I think it would just be a matter of doing it like
this:

object testClass = class_<Test, std::shared_ptr<Test>  >(
   "Test", init<int> ())
   .def("add", &Test::add);

boost::shared_ptr<Test>  test1ptr (new Test (10));
object testObject1 (test1ptr); // ?
// ...

Not too sure of the exact details, but hopefully that gives you the
basic idea. See the libs/python/doc/v2/class.html for details.

-- 
Raoul Gough.
(setq dabbrev-case-fold-search nil)


_______________________________________________
C++-sig mailing list
C++-sig@[...].org
http://mail.python.org/mailman/listinfo/c++-sig