mirrors/cpython
1
0
Fork 0
mirror of https://github.com/python/cpython.git synced 2025-11-17 01:25:57 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 8

bpo-38605: Make 'from __future__ import annotations' the default (GH-20434)

Browse source 
The hard part was making all the tests pass; there are some subtle issues here, because apparently the future import wasn't tested very thoroughly in previous Python versions.

For example, `inspect.signature()` returned type objects normally (except for forward references), but strings with the future import. We changed it to try and return type objects by calling `typing.get_type_hints()`, but fall back on returning strings if that function fails (which it may do if there are future references in the annotations that require passing in a specific namespace to resolve).
This commit is contained in:
Batuhan Taskaya 2020-10-06 23:03:02 +03:00 • committed by GitHub
parent bef7d299eb
commit 044a1048ca
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
27 changed files with 403 additions and 299 deletions
Download patch file Download diff file Expand all files Collapse all files

17
Doc/whatsnew/3.10.rst
View file

@ -70,6 +70,23 @@ Summary -- Release highlights
New Features
============
.. _whatsnew310-pep563:
PEP 563: Postponed Evaluation of Annotations Becomes Default
------------------------------------------------------------
In Python 3.7, postponed evaluation of annotations was added,
to be enabled with a ``from __future__ import annotations``
directive. In 3.10 this became the default behavior, even
without that future directive. With this being default, all
annotations stored in :attr:`__annotations__` will be strings.
If needed, annotations can be resolved at runtime using
:func:`typing.get_type_hints`. See :pep:`563` for a full
description. Also, the :func:`inspect.signature` will try to
resolve types from now on, and when it fails it will fall back to
showing the string annotations. (Contributed by Batuhan Taskaya
in :issue:`38605`.)
* The :class:`int` type has a new method :meth:`int.bit_count`, returning the
number of ones in the binary expansion of a given integer, also known
as the population count. (Contributed by Niklas Fiekas in :issue:`29882`.)