Hi, I am working on exposing a bigint class to python. Now I've got the problem that methods which take an bigint as an parameter do not accept Python longs. For example: import _PythonLiDIA x=123L; c=_PythonLiDIA.bigint(); _PythonLiDIA.gcd(c,x); Traceback (most recent call last): File "test.py", line 132, in ? _PythonLiDIA.gcd(a,x); Boost.Python.ArgumentError: Python argument types in _PythonLiDIA.gcd(bigint, long) did not match C++ signature: gcd(LiDIA::bigint, LiDIA::bigint) I don't know how to achieve implicit conversion at this point, turning an long automatically into an bigint. The other way round, turning an bigint into long can be realized by defining __long__. Can someone help me please? Benjamin