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[Python-Dev] slice subscripts for sequences and mappings

Antoine Pitrou solipsis at pitrou.net
Sat Mar 3 13:48:53 CET 2012 
Le samedi 03 mars 2012 à 14:41 +0200, Eli Bendersky a écrit :
> >> I'd expect slice subscripts to be part of the sequence interface, and
> >> yet they are not. In fact, they are part of the mapping interface. For
> >> example, the list object has its slice get/set methods assigned to a
> >> PyMappingMethods struct. So does a bytes object, and pretty much every
> >> other object that wants to support subscripts.
> >
> > It comes from:
> > http://hg.python.org/cpython/rev/245224d1b8c9
> > http://bugs.python.org/issue400998
> >
> > Written by Michael Hudson and reviewed by Guido.
> > I wonder why this patch chose to add mapping protocol support to tuples
> > and lists, rather than add a tp_ slot for extended slicing.
> >
> 
> Why a separate tp_ slot for extended slicing? ISTM slicing pertains to
> sequences, similarly to other numeric indices. If you look at
> PySequenceMethods it has these (apparently no longer used fields):

Yes, I meant sq_ slot, my bad.

Regards

Antoine.
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