[Numpy-discussion] Array Interface

Thomas Heller theller at python.net
Fri Jun 16 14:49:33 CDT 2006


Travis Oliphant wrote:
> Thanks for the continuing discussion on the array interface.
> 
> I'm thinking about this right now, because I just spent several hours 
> trying to figure out if it is possible to add additional 
> "object-behavior" pointers to a type by creating a metatype that 
> sub-types from the Python PyType_Type (this is the object that has all 
> the function pointers to implement mapping behavior, buffer behavior, 
> etc.).    I found some emails from 2002 where Guido indicates that it is 
> not possible to sub-type the PyType_Type object and add new function 
> pointers at the end without major re-writing of Python.

Yes, but I remember an email from Christian Tismer that it *is* possible.
Although I've never tried that.

What I do in ctypes is to replace the type objects (the subclass of PyType_Type)
dictionary with a subclass of PyDict_Type (in ctypes it is named StgDictObject
- storage dict object, a very poor name I know) that has additional structure fields
describing the C data type it represents.

Thomas





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