Mailman 3 February 2020 - Typing-sig

Runtime Access to Type Parameters
by Saul Shanabrook 07 Jun '23

07 Jun '23

I would like to propose being able to access, at runtime, the type parameters in classmethods and in constructors. I wrote up a draft PEP on this to capture the thinking here: https://github.com/saulshanabrook/peps/blob/master/pep-9999.md It seems easier to add them to classmethods, so even that addition alone would be very welcome! It could be added to Guido's existing draft PR for pep 585, by making a small change in the getattr function (https://github.com/python/cpython/pull/18239/files#diff-a34ae826f869897e56e…), to first do a `__getattribute__` and check if the result is a descriptor (has a `__get__` attribute), and if so passing the generic class itself in as the class, instead of the origin class. I wrote up a little example of that in the PEP. To make it available in the constructor, I proposed adding a global function `get_parameters` to `typing` which returns the parameters in the constructor. I also provide a little mock implementation of that. Note that work is only for custom classes which inherit from `typing.Generic` not for any built in collections.

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Explicit Type Aliases
by Shannon Zhu 17 Aug '22

17 Aug '22

Hi everyone, I’d like to continue the discussion from our last typing summit on explicit type aliases. A quick summary of the current state and the proposal -- Current state: ``` from typing import List x = List[int] # considered a type alias y : Type[List[int]] = List[int] # considered an expression z : Any # considered a type alias z : x = [] # fine z : y = [] # invalid type error ``` Proposal (with explicit aliases): ``` from typing import List, TypeAlias x = TypeAlias[List[int]] # considered a type alias y = List[int] # considered an expression z : Any # considered an expression z = TypeAlias[Any] # considered a type alias reveal_type(x) # Type[List[int]] reveal_type(y) # Any (return type of __getitem__) z : x = [] # fine z : y = [] # invalid type error ``` Some of the benefits we’re hoping to gain from explicit type aliases: * Clearly distinguish between an unannotated global assignment and a type alias, especially when parsing forward-referencing string annotations. * Avoid the confusing case of type aliases in which some part of the type is invalid or undefined. This would facilitate warnings on invalid types at the alias definition rather than later on when the alias is used. * Make valid and invalid types more intuitive to Python programmers by shifting from delineation of non-aliases with a meta annotation toward delineation of aliases with `TypeAlias`. * Remove special treatment of values annotated as `Any`, which currently break all type aliasing rules. This will also allow us to clean up some of the distinctions we maintain between unannotated values and explicit Anys. Note: We also considered denoting the alias as an annotation (e.g. `x: TypeAlias = int`) as an alternative to the syntax above. I’m interested to hear your thoughts and suggestions on making type aliasing explicit going forward – we’d like to start implementing a version of this in Pyre soon! Shannon

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Bay Area Typing Meetup 9/20
by Dominik Gabi 01 Jun '20

01 Jun '20

Jukka and Ivan will be visiting the Bay Area in September and we'd like to organize another meetup. Here are the proposed (tentative) logistics: Date: Friday, Sept. 20 Time: 1pm - 5pm Location: Facebook in Menlo Park (building and room TBD) So far Ivan, Jukka, Guido, Rebecca, Martin (?), and myself have committed to attending. I'm also volunteering the rest of the Pyre team. Please let us know in advance if you plan on attending so that we can book an adequately sized room. Also now's the time to think about topics to discuss or presentations you want to give. – Dominik

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PEP 593: Flexible function and variable annotations
by Till 04 Mar '20

04 Mar '20

Hi, We've just landed pep-593 (https://www.python.org/dev/peps/pep-0593/); it proposes adding support to embed metadata inside type annotations. I'm looking forward to hearing people's opinion. Best, Till

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PyCon 2020 Typing Meetup Agenda
by Shannon Zhu 24 Feb '20

24 Feb '20

Hi everyone, We've secured a space (thanks, Ewa!) for hosting a typing summit this year at PyCon. It will be in Room 321 on Thursday, April 16th from 1-5pm. The summit is a series of presentations and discussions for developers and users of Python static type checking. Everyone interested in this topic is invited to attend! Please fill out this form if you plan on showing up: https://docs.google.com/forms/d/e/1FAIpQLSdBpHqE4XZX62s_iR3uMyllaEdmRB4xSfS… If you have a topic you'd be interested in presenting on, please mention this in the form or email me separately with a title/topic and an estimated amount of time you'll need. I will work on putting together a draft agenda in early March based on expressed interest. Looking forward to seeing you all in April! Shannon

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PEP 612: Parameter Specification Variables
by Mark Mendoza 21 Feb '20

21 Feb '20

Hi All, I want to announce the submission of a new typing PEP, for ParameterSpecifications (https://github.com/python/peps/pull/1259). We discussed this concept at the last typing summit (presentation can be found here https://github.com/facebook/pyre-check/blob/master/docs/Variadic_Type_Varia…), and there seemed to be general consensus on the utility of this idea, and the appropriateness of the particular solution. One note that I know there was some disagreement on was the name for the feature itself, with some folks preferring ArgSpec. I wrote up a brief note in the PEP itself why we're not as big fans of that name, but I'd love to hear all of your opinions on this issue, as well as on anything else in the PEP. Best, Mark Mendoza

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Gitter chat room "typing-dev" created
by Guido van Rossum 07 Feb '20

07 Feb '20

Get it here: https://gitter.im/python/typing-dev I created this so that we'll have a chat room for typing developers that's not so cluttered by newbies. Anyone can join though. -- --Guido van Rossum (python.org/~guido) *Pronouns: he/him **(why is my pronoun here?)* <http://feministing.com/2015/02/03/how-using-they-as-a-singular-pronoun-can-…>

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PEP 613: Explicit Type Aliases
by Shannon Zhu 05 Feb '20

05 Feb '20

Hi everyone, I'm emailing to flag the submission of PEP 613 to formally define the motivation and syntax for explicit type alias. https://github.com/python/peps/pull/1278/files [https://avatars3.githubusercontent.com/u/6366891?s=400&v=4]<https://github.com/python/peps/pull/1278/files> PEP 613: Initial submission by shannonzhu · Pull Request #1278 · python/peps<https://github.com/python/peps/pull/1278/files> Note: Python CLA has been signed but is pending the check at https://check-python-cla.herokuapp.com/ github.com The original discussion on this topic occurred on this list last August (https://mail.python.org/archives/list/typing-sig@python.org/thread/MWRJOBEE…), and the conclusions we reached were hashed out again in the most recent typing meetup at Facebook late last year. Thoughts and opinions on the PEP draft are appreciated! Thanks, Shannon

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PyCon 2020 Typing Summit Plans
by Shannon Zhu 04 Feb '20

04 Feb '20

Hi all, Emailing to ask if there are any plans on convening another typing summit at PyCon this year. If so, it might be around time to start discussing a date/time and a possible agenda! Shannon

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