[Numpy-discussion] Exporting Numpy C functionality to other extension modules

[Jack J. <Jac...@or...>]

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        <Jac...@or...>        
http://www.cwi.nl/~jack -
- If I can't dance I don't want to be part of your revolution -- Emma 
Goldman -