| msg307686 - (view) |
Author: Łukasz Langa (lukasz.langa) *  |
Date: 2017-12-05 21:24 |
| With the patch attached to this issue, @singledispatch gains support for passing the type in @register via annotations. This looks more natural and enables more thorough type checking without repeating yourself: @singledispatch def generic(arg): ... @generic.register def _(arg: str): ... @generic.register def _(arg: int): ... The previous API is still available for backwards compatibility, as well as stacking, and use with classes (sic, I was surprised to learn it's used that way, too). The patch should be uncontroversial, maybe except for the fact that it's importing the `typing` module if annotations are used. This is necessary because of forward references, usage of None as a type, and so on. More importantly, with PEP 563 it's mandatory. |
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| msg307690 - (view) |
Author: Łukasz Langa (lukasz.langa) * |
Date: 2017-12-05 21:40 |
| Guido, I know that you have a lot on your plate right now. Adding you because of PEP 443 and PEP 484. |
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| msg307691 - (view) |
Author: Ivan Levkivskyi (levkivskyi) * |
Date: 2017-12-05 21:42 |
| Idea looks interesting (like a basic runtime @overload). My expectation is that some changes are necessary in mypy for this to work properly. Another (minor) problem is that this creates a circular dependency functools <-> typing. |
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| msg307692 - (view) |
Author: Ivan Levkivskyi (levkivskyi) * |
Date: 2017-12-05 21:43 |
| Oops something wrong happened. |
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| msg307693 - (view) |
Author: Łukasz Langa (lukasz.langa) * |
Date: 2017-12-05 21:58 |
| > this creates a circular dependency functools <-> typing Well, it doesn't since I explicitly import typing inside singledispatch. By the time this import happens, functools is fully imported. This would only be a problem if functools itself tried to use singledispatch with annotations. Not impossible but super unlikely. |
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| msg308075 - (view) |
Author: Łukasz Langa (lukasz.langa) * |
Date: 2017-12-11 21:56 |
| New changeset e56975351bc2c574c728f738e88effba7116279f by Łukasz Langa in branch 'master': bpo-32227: functools.singledispatch supports registering via type annotations (#4733) https://github.com/python/cpython/commit/e56975351bc2c574c728f738e88effba7116279f |
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| msg311565 - (view) |
Author: Cheryl Sabella (cheryl.sabella) * |
Date: 2018-02-03 17:35 |
| Hello, I believe this could be closed as resolved? Do you think it should be added to the What's New? page for 3.7? |
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| msg311599 - (view) |
Author: Ivan Levkivskyi (levkivskyi) * |
Date: 2018-02-04 14:13 |
| > Do you think it should be added to the What's New? page for 3.7? I leave this up to Łukasz. |
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