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"""
The typing module: Support for gradual typing as defined by PEP 484 and subsequent PEPs.
Among other things, the module includes the following:
* Generic, Protocol, and internal machinery to support generic aliases.
All subscripted types like X[int], Union[int, str] are generic aliases.
* Various "special forms" that have unique meanings in type annotations:
NoReturn, Never, ClassVar, Self, Concatenate, Unpack, and others.
* Classes whose instances can be type arguments to generic classes and functions:
TypeVar, ParamSpec, TypeVarTuple.
* Public helper functions: get_type_hints, overload, cast, final, and others.
* Several protocols to support duck-typing:
SupportsFloat, SupportsIndex, SupportsAbs, and others.
* Special types: NewType, NamedTuple, TypedDict.
* Deprecated wrapper submodules for re and io related types.
* Deprecated aliases for builtin types and collections.abc ABCs.
Any name not present in __all__ is an implementation detail
that may be changed without notice. Use at your own risk!
"""
from abc import abstractmethod, ABCMeta
import collections
from collections import defaultdict
import collections.abc
import contextlib
import functools
import operator
import re as stdlib_re # Avoid confusion with the re we export.
import sys
import types
import warnings
from types import WrapperDescriptorType, MethodWrapperType, MethodDescriptorType, GenericAlias
try:
from _typing import _idfunc
except ImportError:
def _idfunc(_, x):
return x
# Please keep __all__ alphabetized within each category.
__all__ = [
# Super-special typing primitives.
'Annotated',
'Any',
'Callable',
'ClassVar',
'Concatenate',
'Final',
'ForwardRef',
'Generic',
'Literal',
'Optional',
'ParamSpec',
'Protocol',
'Tuple',
'Type',
'TypeVar',
'TypeVarTuple',
'Union',
# ABCs (from collections.abc).
'AbstractSet', # collections.abc.Set.
'ByteString',
'Container',
'ContextManager',
'Hashable',
'ItemsView',
'Iterable',
'Iterator',
'KeysView',
'Mapping',
'MappingView',
'MutableMapping',
'MutableSequence',
'MutableSet',
'Sequence',
'Sized',
'ValuesView',
'Awaitable',
'AsyncIterator',
'AsyncIterable',
'Coroutine',
'Collection',
'AsyncGenerator',
'AsyncContextManager',
# Structural checks, a.k.a. protocols.
'Reversible',
'SupportsAbs',
'SupportsBytes',
'SupportsComplex',
'SupportsFloat',
'SupportsIndex',
'SupportsInt',
'SupportsRound',
# Concrete collection types.
'ChainMap',
'Counter',
'Deque',
'Dict',
'DefaultDict',
'List',
'OrderedDict',
'Set',
'FrozenSet',
'NamedTuple', # Not really a type.
'TypedDict', # Not really a type.
'Generator',
# Other concrete types.
'BinaryIO',
'IO',
'Match',
'Pattern',
'TextIO',
# One-off things.
'AnyStr',
'assert_type',
'assert_never',
'cast',
'clear_overloads',
'dataclass_transform',
'final',
'get_args',
'get_origin',
'get_overloads',
'get_type_hints',
'is_typeddict',
'LiteralString',
'Never',
'NewType',
'no_type_check',
'no_type_check_decorator',
'NoReturn',
'NotRequired',
'overload',
'ParamSpecArgs',
'ParamSpecKwargs',
'Required',
'reveal_type',
'runtime_checkable',
'Self',
'Text',
'TYPE_CHECKING',
'TypeAlias',
'TypeGuard',
'Unpack',
]
# The pseudo-submodules 're' and 'io' are part of the public
# namespace, but excluded from __all__ because they might stomp on
# legitimate imports of those modules.
def _type_convert(arg, module=None, *, allow_special_forms=False):
"""For converting None to type(None), and strings to ForwardRef."""
if arg is None:
return type(None)
if isinstance(arg, str):
return ForwardRef(arg, module=module, is_class=allow_special_forms)
return arg
def _type_check(arg, msg, is_argument=True, module=None, *, allow_special_forms=False):
"""Check that the argument is a type, and return it (internal helper).
As a special case, accept None and return type(None) instead. Also wrap strings
into ForwardRef instances. Consider several corner cases, for example plain
special forms like Union are not valid, while Union[int, str] is OK, etc.
The msg argument is a human-readable error message, e.g.::
"Union[arg, ...]: arg should be a type."
We append the repr() of the actual value (truncated to 100 chars).
"""
invalid_generic_forms = (Generic, Protocol)
if not allow_special_forms:
invalid_generic_forms += (ClassVar,)
if is_argument:
invalid_generic_forms += (Final,)
arg = _type_convert(arg, module=module, allow_special_forms=allow_special_forms)
if (isinstance(arg, _GenericAlias) and
arg.__origin__ in invalid_generic_forms):
raise TypeError(f"{arg} is not valid as type argument")
if arg in (Any, LiteralString, NoReturn, Never, Self, TypeAlias):
return arg
if allow_special_forms and arg in (ClassVar, Final):
return arg
if isinstance(arg, _SpecialForm) or arg in (Generic, Protocol):
raise TypeError(f"Plain {arg} is not valid as type argument")
if type(arg) is tuple:
raise TypeError(f"{msg} Got {arg!r:.100}.")
return arg
def _is_param_expr(arg):
return arg is ... or isinstance(arg,
(tuple, list, ParamSpec, _ConcatenateGenericAlias))
def _should_unflatten_callable_args(typ, args):
"""Internal helper for munging collections.abc.Callable's __args__.
The canonical representation for a Callable's __args__ flattens the
argument types, see https://github.com/python/cpython/issues/86361.
For example::
>>> import collections.abc
>>> P = ParamSpec('P')
>>> collections.abc.Callable[[int, int], str].__args__ == (int, int, str)
True
>>> collections.abc.Callable[P, str].__args__ == (P, str)
True
As a result, if we need to reconstruct the Callable from its __args__,
we need to unflatten it.
"""
return (
typ.__origin__ is collections.abc.Callable
and not (len(args) == 2 and _is_param_expr(args[0]))
)
def _type_repr(obj):
"""Return the repr() of an object, special-casing types (internal helper).
If obj is a type, we return a shorter version than the default
type.__repr__, based on the module and qualified name, which is
typically enough to uniquely identify a type. For everything
else, we fall back on repr(obj).
"""
if isinstance(obj, types.GenericAlias):
return repr(obj)
if isinstance(obj, type):
if obj.__module__ == 'builtins':
return obj.__qualname__
return f'{obj.__module__}.{obj.__qualname__}'
if obj is ...:
return('...')
if isinstance(obj, types.FunctionType):
return obj.__name__
return repr(obj)
def _collect_parameters(args):
"""Collect all type variables and parameter specifications in args
in order of first appearance (lexicographic order).
For example::
>>> P = ParamSpec('P')
>>> T = TypeVar('T')
>>> _collect_parameters((T, Callable[P, T]))
(~T, ~P)
"""
parameters = []
for t in args:
if isinstance(t, type):
# We don't want __parameters__ descriptor of a bare Python class.
pass
elif isinstance(t, tuple):
# `t` might be a tuple, when `ParamSpec` is substituted with
# `[T, int]`, or `[int, *Ts]`, etc.
for x in t:
for collected in _collect_parameters([x]):
if collected not in parameters:
parameters.append(collected)
elif hasattr(t, '__typing_subst__'):
if t not in parameters:
parameters.append(t)
else:
for x in getattr(t, '__parameters__', ()):
if x not in parameters:
parameters.append(x)
return tuple(parameters)
def _check_generic(cls, parameters, elen):
"""Check correct count for parameters of a generic cls (internal helper).
This gives a nice error message in case of count mismatch.
"""
if not elen:
raise TypeError(f"{cls} is not a generic class")
alen = len(parameters)
if alen != elen:
raise TypeError(f"Too {'many' if alen > elen else 'few'} arguments for {cls};"
f" actual {alen}, expected {elen}")
def _unpack_args(args):
newargs = []
for arg in args:
subargs = getattr(arg, '__typing_unpacked_tuple_args__', None)
if subargs is not None and not (subargs and subargs[-1] is ...):
newargs.extend(subargs)
else:
newargs.append(arg)
return newargs
def _deduplicate(params, *, unhashable_fallback=False):
# Weed out strict duplicates, preserving the first of each occurrence.
try:
return dict.fromkeys(params)
except TypeError:
if not unhashable_fallback:
raise
# Happens for cases like `Annotated[dict, {'x': IntValidator()}]`
return _deduplicate_unhashable(params)
def _deduplicate_unhashable(unhashable_params):
new_unhashable = []
for t in unhashable_params:
if t not in new_unhashable:
new_unhashable.append(t)
return new_unhashable
def _compare_args_orderless(first_args, second_args):
first_unhashable = _deduplicate_unhashable(first_args)
second_unhashable = _deduplicate_unhashable(second_args)
t = list(second_unhashable)
try:
for elem in first_unhashable:
t.remove(elem)
except ValueError:
return False
return not t
def _remove_dups_flatten(parameters):
"""Internal helper for Union creation and substitution.
Flatten Unions among parameters, then remove duplicates.
"""
# Flatten out Union[Union[...], ...].
params = []
for p in parameters:
if isinstance(p, (_UnionGenericAlias, types.UnionType)):
params.extend(p.__args__)
else:
params.append(p)
return tuple(_deduplicate(params, unhashable_fallback=True))
def _flatten_literal_params(parameters):
"""Internal helper for Literal creation: flatten Literals among parameters."""
params = []
for p in parameters:
if isinstance(p, _LiteralGenericAlias):
params.extend(p.__args__)
else:
params.append(p)
return tuple(params)
_cleanups = []
def _tp_cache(func=None, /, *, typed=False):
"""Internal wrapper caching __getitem__ of generic types.
For non-hashable arguments, the original function is used as a fallback.
"""
def decorator(func):
cached = functools.lru_cache(typed=typed)(func)
_cleanups.append(cached.cache_clear)
@functools.wraps(func)
def inner(*args, **kwds):
try:
return cached(*args, **kwds)
except TypeError:
pass # All real errors (not unhashable args) are raised below.
return func(*args, **kwds)
return inner
if func is not None:
return decorator(func)
return decorator
def _eval_type(t, globalns, localns, recursive_guard=frozenset()):
"""Evaluate all forward references in the given type t.
For use of globalns and localns see the docstring for get_type_hints().
recursive_guard is used to prevent infinite recursion with a recursive
ForwardRef.
"""
if isinstance(t, ForwardRef):
return t._evaluate(globalns, localns, recursive_guard)
if isinstance(t, (_GenericAlias, GenericAlias, types.UnionType)):
if isinstance(t, GenericAlias):
args = tuple(
ForwardRef(arg) if isinstance(arg, str) else arg
for arg in t.__args__
)
is_unpacked = t.__unpacked__
if _should_unflatten_callable_args(t, args):
t = t.__origin__[(args[:-1], args[-1])]
else:
t = t.__origin__[args]
if is_unpacked:
t = Unpack[t]
ev_args = tuple(_eval_type(a, globalns, localns, recursive_guard) for a in t.__args__)
if ev_args == t.__args__:
return t
if isinstance(t, GenericAlias):
return GenericAlias(t.__origin__, ev_args)
if isinstance(t, types.UnionType):
return functools.reduce(operator.or_, ev_args)
else:
return t.copy_with(ev_args)
return t
class _Final:
"""Mixin to prohibit subclassing."""
__slots__ = ('__weakref__',)
def __init_subclass__(cls, /, *args, **kwds):
if '_root' not in kwds:
raise TypeError("Cannot subclass special typing classes")
class _Immutable:
"""Mixin to indicate that object should not be copied."""
__slots__ = ()
def __copy__(self):
return self
def __deepcopy__(self, memo):
return self
class _NotIterable:
"""Mixin to prevent iteration, without being compatible with Iterable.
That is, we could do::
def __iter__(self): raise TypeError()
But this would make users of this mixin duck type-compatible with
collections.abc.Iterable - isinstance(foo, Iterable) would be True.
Luckily, we can instead prevent iteration by setting __iter__ to None, which
is treated specially.
"""
__slots__ = ()
__iter__ = None
# Internal indicator of special typing constructs.
# See __doc__ instance attribute for specific docs.
class _SpecialForm(_Final, _NotIterable, _root=True):
__slots__ = ('_name', '__doc__', '_getitem')
def __init__(self, getitem):
self._getitem = getitem
self._name = getitem.__name__
self.__doc__ = getitem.__doc__
def __getattr__(self, item):
if item in {'__name__', '__qualname__'}:
return self._name
raise AttributeError(item)
def __mro_entries__(self, bases):
raise TypeError(f"Cannot subclass {self!r}")
def __repr__(self):
return 'typing.' + self._name
def __reduce__(self):
return self._name
def __call__(self, *args, **kwds):
raise TypeError(f"Cannot instantiate {self!r}")
def __or__(self, other):
return Union[self, other]
def __ror__(self, other):
return Union[other, self]
def __instancecheck__(self, obj):
raise TypeError(f"{self} cannot be used with isinstance()")
def __subclasscheck__(self, cls):
raise TypeError(f"{self} cannot be used with issubclass()")
@_tp_cache
def __getitem__(self, parameters):
return self._getitem(self, parameters)
class _LiteralSpecialForm(_SpecialForm, _root=True):
def __getitem__(self, parameters):
if not isinstance(parameters, tuple):
parameters = (parameters,)
return self._getitem(self, *parameters)
class _AnyMeta(type):
def __instancecheck__(self, obj):
if self is Any:
raise TypeError("typing.Any cannot be used with isinstance()")
return super().__instancecheck__(obj)
def __repr__(self):
if self is Any:
return "typing.Any"
return super().__repr__() # respect to subclasses
class Any(metaclass=_AnyMeta):
"""Special type indicating an unconstrained type.
- Any is compatible with every type.
- Any assumed to have all methods.
- All values assumed to be instances of Any.
Note that all the above statements are true from the point of view of
static type checkers. At runtime, Any should not be used with instance
checks.
"""
def __new__(cls, *args, **kwargs):
if cls is Any:
raise TypeError("Any cannot be instantiated")
return super().__new__(cls)
@_SpecialForm
def NoReturn(self, parameters):
"""Special type indicating functions that never return.
Example::
from typing import NoReturn
def stop() -> NoReturn:
raise Exception('no way')
NoReturn can also be used as a bottom type, a type that
has no values. Starting in Python 3.11, the Never type should
be used for this concept instead. Type checkers should treat the two
equivalently.
"""
raise TypeError(f"{self} is not subscriptable")
# This is semantically identical to NoReturn, but it is implemented
# separately so that type checkers can distinguish between the two
# if they want.
@_SpecialForm
def Never(self, parameters):
"""The bottom type, a type that has no members.
This can be used to define a function that should never be
called, or a function that never returns::
from typing import Never
def never_call_me(arg: Never) -> None:
pass
def int_or_str(arg: int | str) -> None:
never_call_me(arg) # type checker error
match arg:
case int():
print("It's an int")
case str():
print("It's a str")
case _:
never_call_me(arg) # OK, arg is of type Never
"""
raise TypeError(f"{self} is not subscriptable")
@_SpecialForm
def Self(self, parameters):
"""Used to spell the type of "self" in classes.
Example::
from typing import Self
class Foo:
def return_self(self) -> Self:
...
return self
This is especially useful for:
- classmethods that are used as alternative constructors
- annotating an `__enter__` method which returns self
"""
raise TypeError(f"{self} is not subscriptable")
@_SpecialForm
def LiteralString(self, parameters):
"""Represents an arbitrary literal string.
Example::
from typing import LiteralString
def run_query(sql: LiteralString) -> None:
...
def caller(arbitrary_string: str, literal_string: LiteralString) -> None:
run_query("SELECT * FROM students") # OK
run_query(literal_string) # OK
run_query("SELECT * FROM " + literal_string) # OK
run_query(arbitrary_string) # type checker error
run_query( # type checker error
f"SELECT * FROM students WHERE name = {arbitrary_string}"
)
Only string literals and other LiteralStrings are compatible
with LiteralString. This provides a tool to help prevent
security issues such as SQL injection.
"""
raise TypeError(f"{self} is not subscriptable")
@_SpecialForm
def ClassVar(self, parameters):
"""Special type construct to mark class variables.
An annotation wrapped in ClassVar indicates that a given
attribute is intended to be used as a class variable and
should not be set on instances of that class.
Usage::
class Starship:
stats: ClassVar[dict[str, int]] = {} # class variable
damage: int = 10 # instance variable
ClassVar accepts only types and cannot be further subscribed.
Note that ClassVar is not a class itself, and should not
be used with isinstance() or issubclass().
"""
item = _type_check(parameters, f'{self} accepts only single type.')
return _GenericAlias(self, (item,))
@_SpecialForm
def Final(self, parameters):
"""Special typing construct to indicate final names to type checkers.
A final name cannot be re-assigned or overridden in a subclass.
For example::
MAX_SIZE: Final = 9000
MAX_SIZE += 1 # Error reported by type checker
class Connection:
TIMEOUT: Final[int] = 10
class FastConnector(Connection):
TIMEOUT = 1 # Error reported by type checker
There is no runtime checking of these properties.
"""
item = _type_check(parameters, f'{self} accepts only single type.')
return _GenericAlias(self, (item,))
@_SpecialForm
def Union(self, parameters):
"""Union type; Union[X, Y] means either X or Y.
On Python 3.10 and higher, the | operator
can also be used to denote unions;
X | Y means the same thing to the type checker as Union[X, Y].
To define a union, use e.g. Union[int, str]. Details:
- The arguments must be types and there must be at least one.
- None as an argument is a special case and is replaced by
type(None).
- Unions of unions are flattened, e.g.::
assert Union[Union[int, str], float] == Union[int, str, float]
- Unions of a single argument vanish, e.g.::
assert Union[int] == int # The constructor actually returns int
- Redundant arguments are skipped, e.g.::
assert Union[int, str, int] == Union[int, str]
- When comparing unions, the argument order is ignored, e.g.::
assert Union[int, str] == Union[str, int]
- You cannot subclass or instantiate a union.
- You can use Optional[X] as a shorthand for Union[X, None].
"""
if parameters == ():
raise TypeError("Cannot take a Union of no types.")
if not isinstance(parameters, tuple):
parameters = (parameters,)
msg = "Union[arg, ...]: each arg must be a type."
parameters = tuple(_type_check(p, msg) for p in parameters)
parameters = _remove_dups_flatten(parameters)
if len(parameters) == 1:
return parameters[0]
if len(parameters) == 2 and type(None) in parameters:
return _UnionGenericAlias(self, parameters, name="Optional")
return _UnionGenericAlias(self, parameters)
@_SpecialForm
def Optional(self, parameters):
"""Optional[X] is equivalent to Union[X, None]."""
arg = _type_check(parameters, f"{self} requires a single type.")
return Union[arg, type(None)]
@_LiteralSpecialForm
@_tp_cache(typed=True)
def Literal(self, *parameters):
"""Special typing form to define literal types (a.k.a. value types).
This form can be used to indicate to type checkers that the corresponding
variable or function parameter has a value equivalent to the provided
literal (or one of several literals)::
def validate_simple(data: Any) -> Literal[True]: # always returns True
...
MODE = Literal['r', 'rb', 'w', 'wb']
def open_helper(file: str, mode: MODE) -> str:
...
open_helper('/some/path', 'r') # Passes type check
open_helper('/other/path', 'typo') # Error in type checker
Literal[...] cannot be subclassed. At runtime, an arbitrary value
is allowed as type argument to Literal[...], but type checkers may
impose restrictions.
"""
# There is no '_type_check' call because arguments to Literal[...] are
# values, not types.
parameters = _flatten_literal_params(parameters)
try:
parameters = tuple(p for p, _ in _deduplicate(list(_value_and_type_iter(parameters))))
except TypeError: # unhashable parameters
pass
return _LiteralGenericAlias(self, parameters)
@_SpecialForm
def TypeAlias(self, parameters):
"""Special form for marking type aliases.
Use TypeAlias to indicate that an assignment should
be recognized as a proper type alias definition by type
checkers.
For example::
Predicate: TypeAlias = Callable[..., bool]
It's invalid when used anywhere except as in the example above.
"""
raise TypeError(f"{self} is not subscriptable")
@_SpecialForm
def Concatenate(self, parameters):
"""Special form for annotating higher-order functions.
``Concatenate`` can be used in conjunction with ``ParamSpec`` and
``Callable`` to represent a higher-order function which adds, removes or
transforms the parameters of a callable.
For example::
Callable[Concatenate[int, P], int]
See PEP 612 for detailed information.
"""
if parameters == ():
raise TypeError("Cannot take a Concatenate of no types.")
if not isinstance(parameters, tuple):
parameters = (parameters,)
if not (parameters[-1] is ... or isinstance(parameters[-1], ParamSpec)):
raise TypeError("The last parameter to Concatenate should be a "
"ParamSpec variable or ellipsis.")
msg = "Concatenate[arg, ...]: each arg must be a type."
parameters = (*(_type_check(p, msg) for p in parameters[:-1]), parameters[-1])
return _ConcatenateGenericAlias(self, parameters,
_paramspec_tvars=True)
@_SpecialForm
def TypeGuard(self, parameters):
"""Special typing construct for marking user-defined type guard functions.
``TypeGuard`` can be used to annotate the return type of a user-defined
type guard function. ``TypeGuard`` only accepts a single type argument.
At runtime, functions marked this way should return a boolean.
``TypeGuard`` aims to benefit *type narrowing* -- a technique used by static
type checkers to determine a more precise type of an expression within a
program's code flow. Usually type narrowing is done by analyzing
conditional code flow and applying the narrowing to a block of code. The
conditional expression here is sometimes referred to as a "type guard".
Sometimes it would be convenient to use a user-defined boolean function
as a type guard. Such a function should use ``TypeGuard[...]`` as its
return type to alert static type checkers to this intention.
Using ``-> TypeGuard`` tells the static type checker that for a given
function:
1. The return value is a boolean.
2. If the return value is ``True``, the type of its argument
is the type inside ``TypeGuard``.
For example::
def is_str(val: Union[str, float]):
# "isinstance" type guard
if isinstance(val, str):
# Type of ``val`` is narrowed to ``str``
...
else:
# Else, type of ``val`` is narrowed to ``float``.
...
Strict type narrowing is not enforced -- ``TypeB`` need not be a narrower
form of ``TypeA`` (it can even be a wider form) and this may lead to
type-unsafe results. The main reason is to allow for things like
narrowing ``List[object]`` to ``List[str]`` even though the latter is not
a subtype of the former, since ``List`` is invariant. The responsibility of
writing type-safe type guards is left to the user.
``TypeGuard`` also works with type variables. For more information, see
PEP 647 (User-Defined Type Guards).
"""
item = _type_check(parameters, f'{self} accepts only single type.')
return _GenericAlias(self, (item,))
class ForwardRef(_Final, _root=True):
"""Internal wrapper to hold a forward reference."""
__slots__ = ('__forward_arg__', '__forward_code__',
'__forward_evaluated__', '__forward_value__',
'__forward_is_argument__', '__forward_is_class__',
'__forward_module__')
def __init__(self, arg, is_argument=True, module=None, *, is_class=False):
if not isinstance(arg, str):
raise TypeError(f"Forward reference must be a string -- got {arg!r}")
# If we do `def f(*args: *Ts)`, then we'll have `arg = '*Ts'`.
# Unfortunately, this isn't a valid expression on its own, so we
# do the unpacking manually.
if arg.startswith('*'):
arg_to_compile = f'({arg},)[0]' # E.g. (*Ts,)[0] or (*tuple[int, int],)[0]
else:
arg_to_compile = arg
try:
code = compile(arg_to_compile, '<string>', 'eval')
except SyntaxError:
raise SyntaxError(f"Forward reference must be an expression -- got {arg!r}")
self.__forward_arg__ = arg
self.__forward_code__ = code
self.__forward_evaluated__ = False
self.__forward_value__ = None
self.__forward_is_argument__ = is_argument
self.__forward_is_class__ = is_class
self.__forward_module__ = module
def _evaluate(self, globalns, localns, recursive_guard):
if self.__forward_arg__ in recursive_guard:
return self
if not self.__forward_evaluated__ or localns is not globalns:
if globalns is None and localns is None:
globalns = localns = {}
elif globalns is None:
globalns = localns
elif localns is None:
localns = globalns
if self.__forward_module__ is not None:
globalns = getattr(
sys.modules.get(self.__forward_module__, None), '__dict__', globalns
)
type_ = _type_check(
eval(self.__forward_code__, globalns, localns),
"Forward references must evaluate to types.",
is_argument=self.__forward_is_argument__,
allow_special_forms=self.__forward_is_class__,
)
self.__forward_value__ = _eval_type(
type_, globalns, localns, recursive_guard | {self.__forward_arg__}
)
self.__forward_evaluated__ = True
return self.__forward_value__
def __eq__(self, other):
if not isinstance(other, ForwardRef):
return NotImplemented
if self.__forward_evaluated__ and other.__forward_evaluated__:
return (self.__forward_arg__ == other.__forward_arg__ and
self.__forward_value__ == other.__forward_value__)
return (self.__forward_arg__ == other.__forward_arg__ and
self.__forward_module__ == other.__forward_module__)
def __hash__(self):
return hash((self.__forward_arg__, self.__forward_module__))
def __or__(self, other):
return Union[self, other]
def __ror__(self, other):
return Union[other, self]
def __repr__(self):
if self.__forward_module__ is None:
module_repr = ''
else:
module_repr = f', module={self.__forward_module__!r}'
return f'ForwardRef({self.__forward_arg__!r}{module_repr})'
def _is_unpacked_typevartuple(x: Any) -> bool:
return ((not isinstance(x, type)) and
getattr(x, '__typing_is_unpacked_typevartuple__', False))
def _is_typevar_like(x: Any) -> bool:
return isinstance(x, (TypeVar, ParamSpec)) or _is_unpacked_typevartuple(x)
class _PickleUsingNameMixin:
"""Mixin enabling pickling based on self.__name__."""
def __reduce__(self):
return self.__name__
class _BoundVarianceMixin:
"""Mixin giving __init__ bound and variance arguments.
This is used by TypeVar and ParamSpec, which both employ the notions of
a type 'bound' (restricting type arguments to be a subtype of some
specified type) and type 'variance' (determining subtype relations between
generic types).
"""
def __init__(self, bound, covariant, contravariant):
"""Used to setup TypeVars and ParamSpec's bound, covariant and
contravariant attributes.
"""
if covariant and contravariant:
raise ValueError("Bivariant types are not supported.")
self.__covariant__ = bool(covariant)
self.__contravariant__ = bool(contravariant)
if bound:
self.__bound__ = _type_check(bound, "Bound must be a type.")
else:
self.__bound__ = None
def __or__(self, right):
return Union[self, right]
def __ror__(self, left):
return Union[left, self]
def __repr__(self):
if self.__covariant__:
prefix = '+'
elif self.__contravariant__:
prefix = '-'
else:
prefix = '~'
return prefix + self.__name__
class TypeVar(_Final, _Immutable, _BoundVarianceMixin, _PickleUsingNameMixin,
_root=True):
"""Type variable.
Usage::