On Mon, Jul 23, 2018 at 6:24 AM, Jeroen Demeyer wrote:

On 2018-07-23 11:58, Grégory Lielens wrote:

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Not sure slice[1::3] can be done

It can be done. Since "slice" is a class, it would require a metaclass though.

Another solution that nobody has mentioned (as far as I know) is to add additional syntax to the language for that. For example, one could say that (1:3) could be used to construct slice(1, 3) directly. The parentheses are required to avoid confusion with type hints. I'm not a Python language expert, but I don't think that type hints can occur inside parentheses like that.

If I remember correctly Guido explicitly rejected requests for such syntax. This proposal was intended as a compromise.

2018-07-23 8:16 GMT-07:00 Guido van Rossum :

On Mon, Jul 23, 2018 at 3:24 AM, Jeroen Demeyer wrote:

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On 2018-07-23 11:58, Grégory Lielens wrote:

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Not sure slice[1::3] can be done

It can be done. Since "slice" is a class, it would require a metaclass though.

Since PEP 560 it won't need a metaclass -- it can be implemented as __class_getitem__.

But that brings up the related problem that `slice[]` for creating slice objects would now conflict with typing syntax. And we might reasonably make `slice` generic in the future: https://github.com/python/typing/issues/159.

-- --Guido van Rossum (python.org/~guido)

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Humour warning. Serhiy wrote:

Do you bless using __class_getitem__ for something other than typing?

As in https://perldoc.perl.org/functions/bless.html, perhaps? -- Jonathan

May I propose `slice.L` as in "slice literal": ``` class slice: ... class L: """Slice literal. slice.L[1:2:3, 1] -> (slice(1, 2, 3), slice(1)) """ @classmethod def __class_getitem__(cls, item): return item ``` On Mon, Jul 23, 2018 at 12:02 PM Joseph Jevnik wrote:

I still think that 'operator.subscript' would be valuable to me for all of the same reasons discussed in the previous threads and issues. I don't understand why it was reverted without any serious discussion given that it was already accepted and many people find this useful.

On Mon, Jul 23, 2018 at 2:38 PM, Serhiy Storchaka wrote:

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23.07.18 18:16, Guido van Rossum пише:

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On Mon, Jul 23, 2018 at 3:24 AM, Jeroen Demeyer mailto:J.Demeyer@ugent.be> wrote:

On 2018-07-23 11:58, Grégory Lielens wrote:

Not sure slice[1::3] can be done

It can be done. Since "slice" is a class, it would require a metaclass though.

Since PEP 560 it won't need a metaclass -- it can be implemented as __class_getitem__.

Do you bless using __class_getitem__ for something other than typing?

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