Title: Implementing PEP 649

Author: Jelle Zijlstra <jelle.zijlstra@gmail.com>

Discussions-To: https://discuss.python.org/t/pep-749-implementing-pep-649/54974

Status:Draft

Status:Accepted

Type: Standards Track

Topic: Typing

Requires: 649

Created: 28-May-2024

Python-Version: 3.14

Post-History: `04-Jun-2024<https://discuss.python.org/t/pep-749-implementing-pep-649/54974>`__

Resolution: `05-May-2025<https://discuss.python.org/t/pep-749-implementing-pep-649/54974/66>`__

Abstract

* The ``SOURCE`` format is renamed to ``STRING`` to improve clarity and reduce the risk of

user confusion.

* Conditionally defined class and module annotations are handled correctly.

* If annotations are accessed a partially executed module, the annotations executed so far

* If annotations are accessedona partially executed module, the annotations executed so far

are returned, but not cached.

Motivation

An additional format, ``VALUE_WITH_FAKE_GLOBALS``, is added to the ``Format`` enum in the

``annotationlib`` module, with value equal to 2. (As a result, the values of the

other formats will shift relative to PEP 649: ``FORWARDREF`` will be 3 and ``SOURCE``

will be 4.)

will be 4.) The integer values of these formats are specified for use in places where

the enum is not readily available, such as in ``__annotate__`` functions implemented

in C.

Compiler-generated

annotate functions will support this format and return the same value as

is set only when module execution is complete. This is obviously

unintuitive.

See `python/cpython#130907`__ for implementation.

See `python/cpython#131550`__ for implementation.

Specification