On Sat, Nov 12, 2016 at 11:41 AM, Ivan Levkivskyi <[email protected]> wrote:
> On 12 November 2016 at 20:27, David Mertz <[email protected]> wrote: > >> I thought of the use of `.__getitem__()` in metaclasses in the typing >> module. I feel like this use is more natural and more useful than that. >> Should we someday need a slice generic type for PEP 484, the spelling would >> naturally be `Slice[T]` instead, in my mind. But `slice[1:10,2]` should be >> a constructor for a concrete slice object. >> > > Slice[T] vs slice[::-1] is coherent with what we have now for List[T] vs > list, etc. > Not really. We have List[T] but list[x] is invalid -- it doesn't have a different meaning (it's list instances that support indexing). And in fact the distinction between List and list is intentionally minimal -- List is simply what list wants to become when it grows up. :-) Honestly I think the use case of wanting to create a slice object is rare enough that we can continue to write slice(x, y, z). If you really find yourself wanting something shorter, I believe in the past it's been pointed out that you could create a helper, e.g. like this: class S: def __getitem__(self, x): return x s = S() a = s[:():] -- --Guido van Rossum (python.org/~guido)
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