Begin using Self as return type for __aenter__ methods

This commit bumps the minimum version of typing_extensions to 4.0.0 to
allow the use of "Self" as a type annotation, and changes all the places
where __aenter__ is defined to use this annotation. Thanks go to
Matthew Bradbury for suggesting this and providing a PR for this
change in SSHProcess. This commit is a superset of that PR.

asyncssh/agent.py

@@ -26,7 +26,7 @@
 import sys
 from types import TracebackType
 from typing import TYPE_CHECKING, List, Optional, Sequence, Tuple, Type, Union
-from typing_extensions import Protocol
+from typing_extensions import Protocol, Self
 
 from .listener import SSHForwardListener
 from .misc import async_context_manager, maybe_wait_closed
@@ -198,7 +198,7 @@ def __init__(self, agent_path: _AgentPath):
         self._writer: Optional[AgentWriter] = None
         self._lock = asyncio.Lock()
 
-    async def __aenter__(self) -> 'SSHAgentClient':
+    async def __aenter__(self) -> Self:
         """Allow SSHAgentClient to be used as an async context manager"""
 
         return self

asyncssh/connection.py

@@ -39,7 +39,7 @@
 from typing import TYPE_CHECKING, Any, AnyStr, Awaitable, Callable, Dict
 from typing import List, Mapping, Optional, Sequence, Set, Tuple, Type
 from typing import TypeVar, Union, cast
-from typing_extensions import Protocol
+from typing_extensions import Protocol, Self
 
 from .agent import SSHAgentClient, SSHAgentListener
 
@@ -182,9 +182,8 @@
 _ServerFactory = Callable[[], SSHServer]
 _ProtocolFactory = Union[_ClientFactory, _ServerFactory]
 
-_Conn = TypeVar('_Conn', 'SSHClientConnection', 'SSHServerConnection')
-_ConnSelf = TypeVar('_ConnSelf', bound='SSHConnection')
-_OptionsSelf = TypeVar('_OptionsSelf', bound='SSHConnectionOptions')
+_Conn = TypeVar('_Conn', bound='SSHConnection')
+_Options = TypeVar('_Options', bound='SSHConnectionOptions')
 
 class _TunnelProtocol(Protocol):
     """Base protocol for connections to tunnel SSH over"""
@@ -382,7 +381,7 @@ async def _open_tunnel(tunnels: object, passphrase: Optional[BytesOrStr],
         return None
 
 
-async def _connect(options: '_OptionsSelf', config: DefTuple[ConfigPaths],
+async def _connect(options: '_Options', config: DefTuple[ConfigPaths],
                    loop: asyncio.AbstractEventLoop, flags: int,
                    sock: Optional[socket.socket],
                    conn_factory: Callable[[], _Conn], msg: str) -> _Conn:
@@ -456,7 +455,7 @@ async def _connect(options: '_OptionsSelf', config: DefTuple[ConfigPaths],
             await conn.wait_closed()
 
 
-async def _listen(options: '_OptionsSelf', config: DefTuple[ConfigPaths],
+async def _listen(options: '_Options', config: DefTuple[ConfigPaths],
                   loop: asyncio.AbstractEventLoop, flags: int,
                   backlog: int, sock: Optional[socket.socket],
                   reuse_address: bool, reuse_port: bool,
@@ -677,7 +676,7 @@ def __init__(self, server: asyncio.AbstractServer,
         self._server = server
         self._options = options
 
-    async def __aenter__(self) -> 'SSHAcceptor':
+    async def __aenter__(self) -> Self:
         return self
 
     async def __aexit__(self, _exc_type: Optional[Type[BaseException]],
@@ -942,7 +941,7 @@ def __init__(self, loop: asyncio.AbstractEventLoop,
 
         self._disable_trivial_auth = False
 
-    async def __aenter__(self: _ConnSelf) -> _ConnSelf:
+    async def __aenter__(self) -> Self:
         """Allow SSHConnection to be used as an async context manager"""
 
         return self
@@ -6964,19 +6963,18 @@ class SSHConnectionOptions(Options):
     keepalive_internal: float
     keepalive_count_max: int
 
-    def __init__(self, options: Optional['_OptionsSelf'] = None,
-                 **kwargs: object):
+    def __init__(self, options: Optional['_Options'] = None, **kwargs: object):
         last_config = options.config if options else None
         super().__init__(options=options, last_config=last_config, **kwargs)
 
     @classmethod
-    async def construct(cls, options: Optional['_OptionsSelf'] = None,
-                        **kwargs: object) -> _OptionsSelf:
+    async def construct(cls, options: Optional['_Options'] = None,
+                        **kwargs: object) -> _Options:
         """Construct a new options object from within an async task"""
 
         loop = asyncio.get_event_loop()
 
-        return cast(_OptionsSelf, await loop.run_in_executor(
+        return cast(_Options, await loop.run_in_executor(
             None, functools.partial(cls, options, loop=loop, **kwargs)))
 
     # pylint: disable=arguments-differ

asyncssh/forward.py

@@ -25,6 +25,7 @@
 from types import TracebackType
 from typing import TYPE_CHECKING, Any, Awaitable, Callable, Dict, Optional
 from typing import Type, cast
+from typing_extensions import Self
 
 from .misc import ChannelOpenError, SockAddr
 
@@ -55,7 +56,7 @@ def __init__(self, peer: Optional['SSHForwarder'] = None,
 
         self._extra = extra
 
-    async def __aenter__(self) -> 'SSHForwarder':
+    async def __aenter__(self) -> Self:
         return self
 
     async def __aexit__(self, _exc_type: Optional[Type[BaseException]],

asyncssh/listener.py

@@ -26,6 +26,7 @@
 from types import TracebackType
 from typing import TYPE_CHECKING, AnyStr, Callable, Generic, List, Optional
 from typing import Sequence, Tuple, Type, Union
+from typing_extensions import Self
 
 from .forward import SSHForwarderCoro
 from .forward import SSHLocalPortForwarder, SSHLocalPathForwarder
@@ -54,7 +55,7 @@ class SSHListener:
     def __init__(self) -> None:
         self._tunnel: Optional['SSHConnection'] = None
 
-    async def __aenter__(self) -> 'SSHListener':
+    async def __aenter__(self) -> Self:
         return self
 
     async def __aexit__(self, _exc_type: Optional[Type[BaseException]],

asyncssh/process.py

@@ -33,7 +33,7 @@
 from typing import Any, AnyStr, Awaitable, Callable, Dict, Generic, IO
 from typing import Iterable, List, Mapping, Optional, Set, TextIO
 from typing import Tuple, Type, TypeVar, Union, cast
-from typing_extensions import Protocol
+from typing_extensions import Protocol, Self
 
 from .channel import SSHChannel, SSHClientChannel, SSHServerChannel
 
@@ -747,7 +747,7 @@ def __init__(self, *args) -> None:
 
         self._paused_write_streams: Set[Optional[int]] = set()
 
-    async def __aenter__(self) -> 'SSHProcess[AnyStr]':
+    async def __aenter__(self) -> Self:
         """Allow SSHProcess to be used as an async context manager"""
 
         return self

asyncssh/scp.py

@@ -32,7 +32,7 @@
 from types import TracebackType
 from typing import TYPE_CHECKING, AsyncIterator, List, NoReturn, Optional
 from typing import Sequence, Tuple, Type, Union, cast
-from typing_extensions import Protocol
+from typing_extensions import Protocol, Self
 
 from .constants import DEFAULT_LANG
 from .constants import FILEXFER_TYPE_REGULAR, FILEXFER_TYPE_DIRECTORY
@@ -240,7 +240,7 @@ def __init__(self, reader: 'SSHReader[bytes]', writer: 'SSHWriter[bytes]',
 
         self._logger = reader.logger.get_child('sftp')
 
-    async def __aenter__(self) -> '_SCPHandler': # pragma: no cover
+    async def __aenter__(self) -> Self: # pragma: no cover
         """Allow _SCPHandler to be used as an async context manager"""
 
         return self

asyncssh/sftp.py

@@ -37,7 +37,7 @@
 from typing import TYPE_CHECKING, AnyStr, AsyncIterator, Awaitable, Callable
 from typing import Dict, Generic, IO, Iterable, List, Mapping, Optional
 from typing import Sequence, Set, Tuple, Type, TypeVar, Union, cast, overload
-from typing_extensions import Literal, Protocol
+from typing_extensions import Literal, Protocol, Self
 
 from . import constants
 from .constants import DEFAULT_LANG
@@ -208,7 +208,7 @@ def scandir(self, path: bytes) -> AsyncIterator['SFTPName']:
 class SFTPFileProtocol(Protocol):
     """Protocol for accessing a file via an SFTP server"""
 
-    async def __aenter__(self) -> 'SFTPFileProtocol':
+    async def __aenter__(self) -> Self:
         """Allow SFTPFileProtocol to be used as an async context manager"""
 
     async def __aexit__(self, _exc_type: Optional[Type[BaseException]],
@@ -2999,7 +2999,7 @@ def __init__(self, handler: SFTPClientHandler, handle: bytes,
         self._max_requests = max_requests
         self._offset = None if appending else 0
 
-    async def __aenter__(self) -> 'SFTPClientFile':
+    async def __aenter__(self) -> Self:
         """Allow SFTPClientFile to be used as an async context manager"""
 
         return self
@@ -3463,7 +3463,7 @@ def __init__(self, handler: SFTPClientHandler,
         self._path_errors = path_errors
         self._cwd: Optional[bytes] = None
 
-    async def __aenter__(self) -> 'SFTPClient':
+    async def __aenter__(self) -> Self:
         """Allow SFTPClient to be used as an async context manager"""
 
         return self
@@ -7277,7 +7277,7 @@ class LocalFile:
     def __init__(self, file: _SFTPFileObj):
         self._file = file
 
-    async def __aenter__(self) -> 'LocalFile': # pragma: no cover
+    async def __aenter__(self) -> Self: # pragma: no cover
         """Allow LocalFile to be used as an async context manager"""
 
         return self
@@ -7407,7 +7407,7 @@ def __init__(self, server: SFTPServer, file_obj: object):
         self._server = server
         self._file_obj = file_obj
 
-    async def __aenter__(self) -> 'SFTPServerFile': # pragma: no cover
+    async def __aenter__(self) -> Self: # pragma: no cover
         """Allow SFTPServerFile to be used as an async context manager"""
 
         return self

setup.py

@@ -57,7 +57,9 @@
       long_description = long_description,
       platforms = 'Any',
       python_requires = '>= 3.6',
-      install_requires = ['cryptography >= 39.0', 'typing_extensions >= 3.6'],
+      install_requires = [
+          'cryptography >= 39.0',
+          'typing_extensions >= 4.0.0'],
       extras_require = {
           'bcrypt':     ['bcrypt >= 3.1.3'],
           'fido2':      ['fido2 >= 0.9.2'],