Function Required

Lib/typing.py:3412–3432

Special typing construct to mark a TypedDict key as required. This is mainly useful for total=False TypedDicts. For example:: class Movie(TypedDict, total=False): title: Required[str] year: int m = Movie( title='The Matrix', # typechec

(self, parameters)

@_SpecialForm
def Required(self, parameters):
    """Special typing construct to mark a TypedDict key as required.

    This is mainly useful for total=False TypedDicts.

    For example::

        class Movie(TypedDict, total=False):
            title: Required[str]
            year: int

        m = Movie(
            title='The Matrix',  # typechecker error if key is omitted
            year=1999,
        )

    There is no runtime checking that a required key is actually provided
    when instantiating a related TypedDict.
    """
    item = _type_check(parameters, f'{self._name} accepts only a single type.')
    return _GenericAlias(self, (item,))


@_SpecialForm