Current File : //lib/python3/dist-packages/socksio/compat.py
"""Backport of @functools.singledispatchmethod to Python <3.7.
Adapted from https://github.com/ikalnytskyi/singledispatchmethod
removing 2.7 specific code.
"""
import functools
import typing
if hasattr(functools, "singledispatchmethod"): # pragma: nocover
singledispatchmethod = functools.singledispatchmethod # type: ignore
else:
update_wrapper = functools.update_wrapper
singledispatch = functools.singledispatch
# The type: ignore below is to avoid mypy erroring due to a
# "already defined" singledispatchmethod, oddly this does not
# happen when using `if sys.version_info >= (3, 8)`
class singledispatchmethod(object): # type: ignore
"""Single-dispatch generic method descriptor.
TODO: Figure out how to type this:
`mypy --strict` returns errors like the following for all decorated methods:
"Untyped decorator makes function "send" untyped."
But this is not a normal function-base decorator, it's a class and it
doesn't have a __call__ method. When decorating the "base" method
__init__ is called, but of course its return type is None.
"""
def __init__(self, func: typing.Callable[..., typing.Any]) -> None:
if not callable(func) and not hasattr(func, "__get__"):
raise TypeError("{!r} is not callable or a descriptor".format(func))
self.dispatcher = singledispatch(func)
self.func = func
def register(
self,
cls: typing.Callable[..., typing.Any],
method: typing.Optional[typing.Callable[..., typing.Any]] = None,
) -> typing.Callable[..., typing.Any]:
"""Register a method on a class for a particular type.
Note in Python <= 3.6 this methods cannot infer the type from the
argument's type annotation, users *must* supply it manually on
decoration, i.e.
@my_method.register(TypeToDispatch)
def _(self, arg: TypeToDispatch) -> None:
...
Versus in Python 3.7+:
@my_method.register
def _(self, arg: TypeToDispatch) -> None:
...
"""
# mypy wants method to be non-optional, but it is required to be
# for decoration to work correctly in our case.
# https://github.com/python/cpython/blob/3.8/Lib/functools.py#L887-L920
# is not type annotated either.
return self.dispatcher.register(cls, func=method) # type: ignore
def __get__(
self, obj: typing.Any, cls: typing.Callable[[typing.Any], typing.Any]
) -> typing.Callable[..., typing.Any]:
def _method(*args: typing.Any, **kwargs: typing.Any) -> typing.Any:
method = self.dispatcher.dispatch(args[0].__class__) # type: typing.Any
return method.__get__(obj, cls)(*args, **kwargs)
# The type: ignore below is due to `_method` being given a strict
# "Callable[[VarArg(Any), KwArg(Any)], Any]" which causes a
# 'has no attribute "__isabstractmethod__" error'
# felt safe enough to ignore
_method.__isabstractmethod__ = self.__isabstractmethod__ # type: ignore
_method.register = self.register # type: ignore
update_wrapper(_method, self.func)
return _method
@property
def __isabstractmethod__(self) -> typing.Any:
return getattr(self.func, "__isabstractmethod__", False)
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