utils to inspect Python type annotations
Project description
# typing-utils
Backport Python3.8+ typing utils & issubtype & more
- [API](#api)
[get_origin](#get_origin)
[get_args](#get_args)
[get_type_hints](#get_type_hints)
[issubtype](#issubtype)
![Python 3.6](https://github.com/bojiang/typing_utils/workflows/Python%203.6/badge.svg) ![Python 3.7](https://github.com/bojiang/typing_utils/workflows/Python%203.7/badge.svg) ![Python 3.8](https://github.com/bojiang/typing_utils/workflows/Python%203.8/badge.svg)
## API
[get_origin](#get_origin)
[get_args](#get_args)
[get_type_hints](#get_type_hints)
[issubtype](#issubtype)
### 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:
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:
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.
### 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:
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
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