[C++-sig] Wrapping shared_ptr of virtual classes

[Will Lee]

I have seen this post (
http://aspn.activestate.com/ASPN/Mail/Message/cpp-sig/2262721) a while a go
but I couldn't find the response that solves this problem.  Essentially, I
couldn't find a way to wrap an abstract class that is being returned as a
shared_ptr.  For the following scenario:

class A has virtual method f
class B inherits from A that implements f
class F that has a static method: shared_ptr<A> getInstance()

Essentially I want to call F.getInstance().f() in python, which will call
B::f

All the documentation points to creating a wrapper class, so I have done so:

struct AWrapper : A, wrapper<A>
(would wrap function "f" that uses this->get_override() call to call the
overridden function)

My question is, like what is in the post, how do I declare class A?

I don't think I can declare the AWrapper, since F.getInstance() returns
shared_ptr<A> and not shared_ptr<AWrapper>:

class_<AWrapper, shared_ptr<AWrapper>, boost::noncopyable>...

I don't think I can declare with A either, since how can I tie the wrapper
function calls?

class_<A, shared_ptr<A>, boost::noncopyable>

Then this just gets me confused in what it would do (I got a convert error
saying that there is no to_python converter found):

class_<A, AWrapper, shared_ptr<A>, boost::noncopyable>

...

Your help is greatly appreciated.

Will
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