Backport Python 3.8+ typing utils & add issubtype & more

Related tags

Linters & Style Checkers typing_utils
Overview

typing-utils

Backport Python3.8+ typing utils & issubtype & more

Downloads
Python 3.6 Python 3.7 Python 3.8 Python 3.9

Install

    pip install typing_utils

API

issubtype

Check that the left argument is a subtype of the right.

For unions, check if the type arguments of the left is a subset of the right. Also works for nested types including ForwardRefs.

Examples:

    from typing_utils import issubtype

    issubtype(typing.List, typing.Any) == True
    issubtype(list, list) == True
    issubtype(list, typing.List) == True
    issubtype(list, typing.Sequence) == True
    issubtype(typing.List[int], list) == True
    issubtype(typing.List[typing.List], list) == True
    issubtype(list, typing.List[int]) == False
    issubtype(list, typing.Union[typing.Tuple, typing.Set]) == False
    issubtype(typing.List[typing.List], typing.List[typing.Sequence]) == True
    JSON = typing.Union[
        int, float, bool, str, None, typing.Sequence["JSON"],
        typing.Mapping[str, "JSON"]
    ]
    issubtype(str, JSON, forward_refs={'JSON': JSON}) == True
    issubtype(typing.Dict[str, str], JSON, forward_refs={'JSON': JSON}) == True
    issubtype(typing.Dict[str, bytes], JSON, forward_refs={'JSON': JSON}) == False

get_origin

Get the unsubscripted version of a type.

This supports generic types, Callable, Tuple, Union, Literal, Final and ClassVar. Return None for unsupported types.

Examples:

    from typing_utils import get_origin

    get_origin(Literal[42]) is Literal
    get_origin(int) is None
    get_origin(ClassVar[int]) is ClassVar
    get_origin(Generic) is Generic
    get_origin(Generic[T]) is Generic
    get_origin(Union[T, int]) is Union
    get_origin(List[Tuple[T, T]][int]) == list

get_args

Get type arguments with all substitutions performed.

For unions, basic simplifications used by Union constructor are performed.

Examples:

    from typing_utils import get_args

    get_args(Dict[str, int]) == (str, int)
    get_args(int) == ()
    get_args(Union[int, Union[T, int], str][int]) == (int, str)
    get_args(Union[int, Tuple[T, int]][str]) == (int, Tuple[str, int])
    get_args(Callable[[], T][int]) == ([], int)

get_type_hints

Return type hints for an object.

This is often the same as obj.annotations, but it handles forward references encoded as string literals, and if necessary adds Optional[t] if a default value equal to None is set.

The argument may be a module, class, method, or function. The annotations are returned as a dictionary. For classes, annotations include also inherited members.

TypeError is raised if the argument is not of a type that can contain annotations, and an empty dictionary is returned if no annotations are present.

BEWARE -- the behavior of globalns and localns is counterintuitive (unless you are familiar with how eval() and exec() work). The search order is locals first, then globals.

  • If no dict arguments are passed, an attempt is made to use the globals from obj (or the respective module's globals for classes), and these are also used as the locals. If the object does not appear to have globals, an empty dictionary is used.

  • If one dict argument is passed, it is used for both globals and locals.

  • If two dict arguments are passed, they specify globals and locals, respectively.

Comments
  • Add testing against Python 3.9

    Add testing against Python 3.9

    I'm trying this library on Python 3.9, and specifically interested in the issubtype() call - I haven't found a good alternative anywhere.

    It's failing on a call to issubclass() with typing.Optional - so I wanted to see if the tests would pass here on Python 3.9 before digging deeper.

    opened by miketheman 4
  • Couple of errors in overrides issues

    Couple of errors in overrides issues

    https://github.com/mkorpela/overrides/issues/78

    https://github.com/mkorpela/overrides/issues/79

    I think I need to insert this package code to overrides, if it seems there is no maintenance. Basically the issues are now in overrides production, so I need to fix them fast. I can move back to using this library if there is a fixing release (I can also make a PR for that).

    opened by mkorpela 2
  • The infamous TypeVar

    The infamous TypeVar

    Hi all, Nice lib :) We've been trying to get signature checking to overrides. TypeVar is making my head hurt. 😢 I wish it would work with issubtype but now getting results that kind of point that the method should give three possible results: Yes, No, Unknown..

    from typing_utils import issubtype
from typing import TypeVar
T = TypeVar("T")
K = TypeVar("K")
C = TypeVar("C", bound=str)
issubtype(str, T) # -> throws error, I think it should be unknown
issubtype(T, T) # -> True -> and ok
issubtype(K, T) # -> False ... hmm, I think it should be unknown
issubtype(T, int) # -> False ... hmm, I think it should be unknown
issubtype(C, str) # -> False -> should in my opinion be True

    Sincerely, your biggest user https://pypistats.org/packages/typing-utils ;)

    opened by mkorpela 1
  • fix: list args of Callable

    fix: list args of Callable

    Changes: https://github.com/bojiang/typing_utils/pull/6/files#diff-556812789bdf8b0b5fa491afe93530be33abb8fd41150bec1da8da6b7c43e064R128 Context: fix #5

    opened by bojiang 0
  • Literal is broken

    Literal is broken

    After the recent pull request, issubtype produces incorrect results for Literals and exceptions when string literals are used.

    EDIT: apparently the incorrect behavior was there already before, but now instead of RecursionError there is another error

    opened by apirogov 2
Releases(v0.1.0)
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