Hello David,
2b. Now, suppose we have one more derived class: class Base { ... }; class Derived: public Base { ... }; class HiddenImplementation: public Derived { ... }; with Derived being no more than an interface. Naturally, we don't want to export HiddenImplementation to Python, but still want to retain automatic conversions from Base* to Derived* whenever pointer to HiddenImplementation object is passed to Python. Any way to do this? Without hack-ins?
DA> Not without a hack, no. But the hack might be simple: DA> #include <boost/python/object/inheritance.hpp> // non-public implementation details DA> ... DA> boost::python::object::register_conversion<Derived,HiddenImplementation>(); DA> boost::python::object::register_conversion<HiddenImplementation,Derived>(); Thanks again for the advice---though it didn't work as is, I was able to track down the reason, and came up with a solution. Here it is, in case you, or anyone else, is interested. First, I should mention that such conversions for function args passed from Python are always there---even if we don't mention implementation class in the extension module at all. What disappears in the latter case, is similar conversions for values being returned to Python. The solution is actually to pretend that HiddenImp objects are some sort of Derived ones: objects::copy_class_object( type_id< Derived >(), type_id< HiddenImplementation >() ); instead of calling "class_< HiddenImplementation >...". As before, we don't even need access to actual HiddenImp declaration. It is enough to have a fake class HiddenImplementation: public Derived { }; one. At least, it is enough for MSVC, and HiddenImplementation defined in a separate DLL and not mentioned anywhere else in the extension module. -- Best regards, Vladimir mailto:ardatur@mail.ru