The typing_extensions
module contains both backports of typing
features as well as experimental types that will eventually be added to the typing
module, such as Protocol
(see PEP 544 for details about protocols and static duck typing) or TypedDict
(see PEP 589).
Users of other Python versions should continue to install and use the typing
module from PyPi instead of using this one unless specifically writing code that must be compatible with multiple Python versions or requires experimental types.
This module currently contains the following:
Annotated
AsyncContextManager
AsyncGenerator
AsyncIterable
AsyncIterator
Awaitable
ChainMap
ClassVar
Concatenate
ContextManager
Coroutine
Counter
DefaultDict
Deque
final
Final
Literal
NewType
NoReturn
overload
(note that older versions oftyping
only let you useoverload
in stubs)OrderedDict
ParamSpec
ParamSpecArgs
ParamSpecKwargs
Protocol
runtime_checkable
Text
Type
TypedDict
TypeAlias
TypeGuard
TYPE_CHECKING
There are a few types whose interface was modified between different versions of typing. For example, typing.Sequence
was modified to subclass typing.Reversible
as of Python 3.5.3.
These changes are _not backported to prevent subtle compatibility issues when mixing the differing implementations of modified classes.
Certain types have incorrect runtime behavior due to limitations of older versions of the typing module. For example, ParamSpec
and Concatenate
will not work with get_args
, get_origin
. Certain PEP 612 special cases in user-defined Generic
s are also not available. These types are only guaranteed to work for static type checking.
To run tests, navigate into the appropriate source directory and run test_typing_extensions.py
. You will also need to install the latest version of typing
if you are using a version of Python that does not include typing
as a part of the standard library.