On Thu, Dec 16, 2010 at 7:18 AM, Dave Abrahams <dave@boostpro.com> wrote:
At Mon, 13 Dec 2010 10:56:25 +1100, Allan Johns wrote:
Right you are.
With regards to my original snippet:
template<typename Attrib> struct typed_attrib_topython { static PyObject* convert(const Attrib& a) { return bp::incref(bp::object(a.value()).ptr()); // return
POD
type } };
template<typename T> struct TypedAttribBind { typedef TypedAttribute<T> attrib_t;
TypedAttribBind() { boost::python::to_python_converter<attrib_t, typed_attrib_topython<attrib_t> >(); } };
TypedAttribute<T> derives from Attribute, which derives from Object (the common polymorphic base class). TypedAttribute<T>.value() is a function which returns the POD type associated with the attribute. TypedAttribBind<T> is instantiated for a range of POD types T, in order to register the to-python converters.
This doesn't behave as expected - if I call any bound function which returns a shared_ptr<Object> from python (where the object is actually a TypedAttribute<T>), I just get a wrapped Object back, rather than a POD type.
I *think* what you mean is that you don't get a Python built-in type (since POD is a C++ concept and you're looking at the resulting object from the Python side)?
Yes sorry I was inferring built-in python types that are analogous to C++ POD types (float, int etc).
I'm afraid shared_ptr<T> is treated specially by Boost.Python at an extremely low level, so this is hard to do. However, although I can't support this usage, you might take a look in boost/python/converter/shared_ptr_to_python.hpp and consider creating an overload (in namespace boost::python::converter) for shared_ptr<Object>.
Ok thanks, I'll take a look at that. Cheers! A
-- Dave Abrahams BoostPro Computing http://www.boostpro.com
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