Actually, wrt my previous message on cobjects for communicating between extension modules, we can do one better! This is an idea I've been toying with for the MacPython extension types, and I think it's applicable to Numeric too. It goes as follows. Each Numeric object has an attribute with a well-known name, lets call it "__Numeric_C_interface". This is a Cobject, and it is shared among all Numeric objects of the same type. The value of this C object is a pointer to a C structure with pointers to all the C routines you might want to call on the object, basically the PyArray_API structure (I think). The descr of the C object is a string with the version number of this particular PyArray_API structure. An extension module that knows about this protocol and gets passed an object that it think might be a Numeric array checks whether the object has an __Numeric_C_interface attribute. If so it retrieves it, checks that it is a Cobject, gets the descriptor and tests it for compatibility and if it is compatible gets the cobject pointer and happily calls all the Numeric routines it needs. -- - Jack Jansen <Jack.Jansen@oratrix.com> http://www.cwi.nl/~jack - - If I can't dance I don't want to be part of your revolution -- Emma Goldman -