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Do not advertise to create your own assert_never helper #15947

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Aug 24, 2023
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Do not advertise to create your own assert_never helper #15947

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10 changes: 2 additions & 8 deletions docs/source/literal_types.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -329,13 +329,10 @@ perform an exhaustiveness check, you need to update your code to use an
.. code-block:: python

from typing import Literal, NoReturn
from typing_extensions import assert_never

PossibleValues = Literal['one', 'two']

def assert_never(value: NoReturn) -> NoReturn:
# This also works at runtime as well
assert False, f'This code should never be reached, got: {value}'

def validate(x: PossibleValues) -> bool:
if x == 'one':
return True
Expand Down Expand Up @@ -443,10 +440,7 @@ Let's start with a definition:

from enum import Enum
from typing import NoReturn

def assert_never(value: NoReturn) -> NoReturn:
# This also works in runtime as well:
assert False, f'This code should never be reached, got: {value}'
from typing_extensions import assert_never

class Direction(Enum):
up = 'up'
Expand Down