[C++-sig] Exposing virtual functions with default implementations

[Piotr Jaroszynski]

Hello,

I am a little confused by Boost.Python tutorial about this subject - [1]. It 
is saying that I need to both override and make a default_ for a function I 
want to expose, but why is it really needed? Just the override w/o using the 
special def function seems enough - [2], [3]. What am I missing here?
 
[1] - 
http://www.boost.org/libs/python/doc/tutorial/doc/html/python/exposing.html#python.virtual_functions_with_default_implementations
[2] - http://dev.gentooexperimental.org/~peper/boost/test_virtual.cc
[3] - http://dev.gentooexperimental.org/~peper/boost/test_virtual.py

-- 
Best Regards,
Piotr Jaroszynski