Ralf W. Grosse-Kunstleve wrote:

This could be connected to missing pickle support. I think copy.copy() essentially pickles/unpickles to make the copy. I'd think if you add pickle support to your class it will work. I'm not sure about the details. See the "pickle suite" docs (link on main Boost.Python page). Ralf

Thanks, this certainly seems to be the case. If I add ".enable_pickling()" to my Base class definition, then the example I posted works as expected. However, if I then modify the Derived class constructor so that it takes an argument, e.g.: class Derived(Base): def __init__(self, arg): Base.__init__(self) d = Derived(None) func(d) d_copy = copy.copy(d) func(d_copy) I get an error such as: Traceback (most recent call last): File "test.py", line 20, in <module> d_copy = copy.copy(d) File "python2.5/copy.py", line 95, in copy return _reconstruct(x, rv, 0) File "python2.5/copy.py", line 322, in _reconstruct y = callable(*args) TypeError: __init__() takes exactly 2 arguments (1 given) Cheers, Mark