bpo-36972: Add SupportsIndex (GH-13448)

In order to support typing checks calling hex(), oct() and bin() on user-defined classes, a SupportIndex protocol is required. The ability to check these at runtime would be good to add for completeness sake. This is pretty much just a copy of SupportsInt with the names tweaked.
This commit is contained in:
Paul Dagnelie 2019-05-22 07:23:01 -07:00 committed by Ivan Levkivskyi
parent 33e71e01e9
commit 4c7a46eb3c
5 changed files with 21 additions and 0 deletions

View File

@ -529,6 +529,12 @@ The module defines the following classes, functions and decorators:
An ABC with one abstract method ``__bytes__``.
.. class:: SupportsIndex
An ABC with one abstract method ``__index__``.
.. versionadded:: 3.8
.. class:: SupportsAbs
An ABC with one abstract method ``__abs__`` that is covariant

View File

@ -568,6 +568,10 @@ class ProtocolTests(BaseTestCase):
self.assertIsSubclass(list, typing.Reversible)
self.assertNotIsSubclass(int, typing.Reversible)
def test_supports_index(self):
self.assertIsSubclass(int, typing.SupportsIndex)
self.assertNotIsSubclass(str, typing.SupportsIndex)
def test_protocol_instance_type_error(self):
with self.assertRaises(TypeError):
isinstance(0, typing.SupportsAbs)

View File

@ -74,6 +74,7 @@ __all__ = [
'SupportsBytes',
'SupportsComplex',
'SupportsFloat',
'SupportsIndex',
'SupportsInt',
'SupportsRound',
@ -1304,6 +1305,14 @@ class SupportsBytes(_Protocol):
pass
class SupportsIndex(_Protocol):
__slots__ = ()
@abstractmethod
def __index__(self) -> int:
pass
class SupportsAbs(_Protocol[T_co]):
__slots__ = ()

View File

@ -355,6 +355,7 @@ Tom Culliton
Raúl Cumplido
Antonio Cuni
Brian Curtin
Paul Dagnelie
Lisandro Dalcin
Darren Dale
Andrew Dalke

View File

@ -0,0 +1 @@
Add SupportsIndex protocol to the typing module to allow type checking to detect classes that can be passed to `hex()`, `oct()` and `bin()`.