[Python-Dev] PEP for adding an sq_index slot so that any object, a or b, can be used in X[a:b] notation (original) (raw)

Travis E. Oliphant oliphant.travis at ieee.org
Thu Feb 9 22:40:29 CET 2006

Bengt Richter wrote:

How about if SLICE byte code interpretation would try to call obj.int() if passed a non-(int,long) obj ? Would that cover your use case?

I believe that this is pretty much what I'm proposing (except I'm not proposing to use the int method because it is already used as coercion and doing this would allow floats to be used in slices which is a bad thing). The apply_slice and assign_slice functions in ceval.c are called for the SLICE and STORE_SLICE and DELETE_SLICE opcodes.

BTW the slice type happily accepts anything for start:stop:step I believe, and something[slice(whatever)] will call something.getitem with the slice instance, though this is neither a fast nor nicely spelled way to customize.

Yes, the slice object itself takes whatever you want. However, Python special-cases what happens for X[a:b] if X as the sequence-protocol defined. This is the code-path I'm trying to enhance.

-Travis

More information about the Python-Dev mailing list