JelleZijlstra

This contains some notes in connection to an in-progress PEP about deprecation support in the type system.

Briefly, the proposals being considered are:

• @deprecated decorator for functions and classes
• Deprecated[T] modifier for parameter and attribute types

I looked for usage of deprecations in the CPython codebase and whether some variation of this proposal could cover them, in the sense that it would be possible to write a stub that allows type checkers to detect code that would trigger the deprecation.

JelleZijlstra

% flake8 --select=Y093 stdlib stubs 
stdlib/zipapp.pyi:5:1: Y093 Use typing_extensions.TypeAlias for type aliases
stdlib/profile.pyi:10:1: Y093 Use typing_extensions.TypeAlias for type aliases
stdlib/socketserver.pyi:7:1: Y093 Use typing_extensions.TypeAlias for type aliases
stdlib/socketserver.pyi:8:1: Y093 Use typing_extensions.TypeAlias for type aliases
stdlib/gzip.pyi:9:1: Y093 Use typing_extensions.TypeAlias for type aliases
stdlib/gzip.pyi:10:1: Y093 Use typing_extensions.TypeAlias for type aliases
stdlib/gzip.pyi:11:1: Y093 Use typing_extensions.TypeAlias for type aliases
stdlib/itertools.pyi:24:1: Y093 Use typing_extensions.TypeAlias for type aliases
stdlib/itertools.pyi:26:1: Y093 Use typing_extensions.TypeAlias for type aliases

JelleZijlstra

def _parse_callable_arg_list(args: Sequence[object]) -> Sequence[SigParameter]:
    return [
        SigParameter(f".arg{i}", ParameterKind.POSITIONAL_ONLY, annotation=parse_type(arg))
        for i, arg in enumerate(args)
    ]

# Proposed "nested" approach

def parse_callable(node: Union[CallableType, AsyncCallableType]) -> Value:
    return_value = parse_type(node.returns)

JelleZijlstra

Only in stdlib/3/: cgi.pyi  # done
Only in stdlib/2/: commands.pyi  # removed in py3
Only in stdlib/2/: compileall.pyi  # done
Only in stdlib/3/: concurrent  # new in 3
Only in stdlib/2/: cookielib.pyi  # moved
Only in stdlib/3/: curses
Only in stdlib/3/: dis.pyi  # done
Only in stdlib/2/: distutils
Only in stdlib/2/: exceptions.pyi  # removed in py3
Only in stdlib/2/: future_builtins.pyi  # removed in py3

JelleZijlstra

$ diff stdlib/3/codecs.pyi stdlib/2and3/codecs.pyi 
2c2
< # https://docs.python.org/3/library/codecs.html
---
> # https://docs.python.org/2/library/codecs.html and https://docs.python.org/3/library/codecs.html
17c17
< # bytes is the raw form and str is the cooked form.
---
> # bytes (py2 str) is the raw form and str (py2 unicode) is the cooked form.
19a20

JelleZijlstra

$ diff stdlib/2/codecs.pyi stdlib/2and3/codecs.pyi 
2c2
< # https://docs.python.org/2/library/codecs.html
---
> # https://docs.python.org/2/library/codecs.html and https://docs.python.org/3/library/codecs.html
9d8
<     Optional,
18c17
< # str is the raw form and unicode is the cooked form.
---

JelleZijlstra

$ diff stdlib/2/codecs.pyi stdlib/3/codecs.pyi 
2c2
< # https://docs.python.org/2/library/codecs.html
---
> # https://docs.python.org/3/library/codecs.html
9d8
<     Optional,
18c17
< # str is the raw form and unicode is the cooked form.
---