1  from __future__ import annotations
   2  
   3  from abc import ABCMeta, abstractmethod
   4  from types import TracebackType
   5  from typing import TypeVar
   6  
   7  T = TypeVar("T")
   8  
   9  
  10  class AsyncResource(metaclass=ABCMeta):
  11      """
  12      Abstract base class for all closeable asynchronous resources.
  13  
  14      Works as an asynchronous context manager which returns the instance itself on enter,
  15      and calls :meth:`aclose` on exit.
  16      """
  17  
  18      __slots__ = ()
  19  
  20      async def __aenter__(self: T) -> T:
  21          return self
  22  
  23      async def __aexit__(
  24          self,
  25          exc_type: type[BaseException] | None,
  26          exc_val: BaseException | None,
  27          exc_tb: TracebackType | None,
  28      ) -> None:
  29          await self.aclose()
  30  
  31      @abstractmethod
  32      async def aclose(self) -> None:
  33          """Close the resource."""
  34