Function NamedTuple

Lib/typing.py:3041–3105

Typed version of namedtuple. Usage:: class Employee(NamedTuple): name: str id: int This is equivalent to:: Employee = collections.namedtuple('Employee', ['name', 'id']) The resulting class has an extra __annotations__ attribute, giving a d

(typename, fields=_sentinel, /, **kwargs)

def NamedTuple(typename, fields=_sentinel, /, **kwargs):
    """Typed version of namedtuple.

    Usage::

        class Employee(NamedTuple):
            name: str
            id: int

    This is equivalent to::

        Employee = collections.namedtuple('Employee', ['name', 'id'])

    The resulting class has an extra __annotations__ attribute, giving a
    dict that maps field names to types.  (The field names are also in
    the _fields attribute, which is part of the namedtuple API.)
    An alternative equivalent functional syntax is also accepted::

        Employee = NamedTuple('Employee', [('name', str), ('id', int)])
    """
    if fields is _sentinel:
        if kwargs:
            deprecated_thing = "Creating NamedTuple classes using keyword arguments"
            deprecation_msg = (
                "{name} is deprecated and will be disallowed in Python {remove}. "
                "Use the class-based or functional syntax instead."
            )
        else:
            deprecated_thing = "Failing to pass a value for the 'fields' parameter"
            example = f"`{typename} = NamedTuple({typename!r}, [])`"
            deprecation_msg = (
                "{name} is deprecated and will be disallowed in Python {remove}. "
                "To create a NamedTuple class with 0 fields "
                "using the functional syntax, "
                "pass an empty list, e.g. "
            ) + example + "."
    elif fields is None:
        if kwargs:
            raise TypeError(
                "Cannot pass `None` as the 'fields' parameter "
                "and also specify fields using keyword arguments"
            )
        else:
            deprecated_thing = "Passing `None` as the 'fields' parameter"
            example = f"`{typename} = NamedTuple({typename!r}, [])`"
            deprecation_msg = (
                "{name} is deprecated and will be disallowed in Python {remove}. "
                "To create a NamedTuple class with 0 fields "
                "using the functional syntax, "
                "pass an empty list, e.g. "
            ) + example + "."
    elif kwargs:
        raise TypeError("Either list of fields or keywords"
                        " can be provided to NamedTuple, not both")
    if fields is _sentinel or fields is None:
        import warnings
        warnings._deprecated(deprecated_thing, message=deprecation_msg, remove=(3, 15))
        fields = kwargs.items()