Unfortunate exception on dict item assignment (and why aren't slices hashable?)
Anders J. Munch
andersjm at dancontrol.dk
Tue Jul 29 03:51:44 EDT 2003
"Aahz" <aahz at pythoncraft.com> wrote:
> Jeff Epler <jepler at unpythonic.net> wrote:
> >
> >I don't see what's problematic about letting slices be hashable:
> [...]
>Hashing them as
> > hash((s.start,s.stop,s.step))
> >might be a reasonable definition.
>
> Makes sense to me. Feel free to submit a patch to SF. ;-)
I'd rather he didn't. I prefer Python to be able to catch the bug of
attempting to use a dict as were it a list. For the rare case where
using a slice key was intentional, converting to tuple form is easy
enough.
I can see that it's good for consistency to allow hashing of slices.
However it's bad for consistency that where alist[slice] returns a
subsequence, adict[slice] would return a single element.
- Anders
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