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Description:

futuretyping 0.4.1

future-typing

Use generic type hints and new union syntax | with python 3.6+
If you just want to use new annotations for type checkers like mypy, then do not use this library
and simply add from __future__ import annotations.
But if you want to use those annotations at runtime, then you may be at the right place!
This library exposes:

transform_annotation, which will transform list[str|int|float] into

typing.List[typing.Union[str, int, float]] for python 3.6 to 3.8
list[typing.Union[str, int, float]] for python 3.9 (since generic types are natively supported)

a custom source code encoding future_typing that you can use to trigger the transformation at
interpretation time

a CLI to see the transformed source

Installation
pip install future_typing

Codec
Just add this custom source code encoding at the top of your file
# -*- coding: future_typing -*-

and then use | and list[str], dict[str, int], ... as if you were using python 3.10
# -*- coding: future_typing -*-
from typing import Literal

class C:
@staticmethod
def g(t: tuple[int, ...]) -> tuple[int, ...]:
return t

def f(a: list[str | int] | dict[str, str], b: Literal['pika'] | None = None) -> type[C]:
x: set[str | int] = set(a)
y: frozenset[str] = frozenset(['y1', 'y2'])
t: tuple[int, ...] = (1, 2)
print(f'it works! a: {a!r}, b: {b!r}')
return C

f(['a', 'b', 1], 'pika')

$ python3.8 pika.py
it works! a: ['a', 'b'], b: 'pika'

$ mypy pika.py
Success: no issues found in 1 source file

CLI
$ future_typing pika.py
import typing as typing___
from typing import Literal

class C :
@staticmethod
def g (t :typing___.Tuple [int ,...])->typing___.Tuple [int ,...]:
return t

def f (a :typing___.Union [typing___.List [typing___.Union [str ,int ]],typing___.Dict [str ,str ]],b :typing___.Union [Literal ['pika'],None ]=None )->typing___.Type [C ]:
x :typing___.Set [typing___.Union [str ,int ]]=set (a )
y :typing___.FrozenSet [str ]=frozenset (['y1','y2'])
t :typing___.Tuple [int ,...]=(1 ,2 )
print (f'it works! a: {a!r}, b: {b!r}')
return C

f (['a','b',1 ],'pika')