Add type stubs for asyncio.unix_events (#3664)

* add 3.7 child watchers

Signed-off-by: Oleg Höfling <oleg.hoefling@gmail.com>

* add 3.8 child watchers

Signed-off-by: Oleg Höfling <oleg.hoefling@gmail.com>

* remove 3.7 check

Signed-off-by: Oleg Höfling <oleg.hoefling@gmail.com>

* fix too strict watcher return type in _UnixDefaultEventLoopPolicy.get_child_watcher

Signed-off-by: Oleg Höfling <oleg.hoefling@gmail.com>

* group asyncio imports

Signed-off-by: Oleg Höfling <oleg.hoefling@gmail.com>

* fixed platform check for importing from asyncio.unix_events

Signed-off-by: Oleg Höfling <oleg.hoefling@gmail.com>

stdlib/3/asyncio/__init__.pyi

@@ -112,8 +112,13 @@ if sys.version_info >= (3, 7):
 if sys.platform != 'win32':
     # This is already imported above on Windows.
     SelectorEventLoop: Type[AbstractEventLoop]
-
-# TODO: AbstractChildWatcher (UNIX only)
+    from .unix_events import (
+        AbstractChildWatcher as AbstractChildWatcher,
+        BaseChildWatcher as BaseChildWatcher,
+        SafeChildWatcher as SafeChildWatcher,
+    )
+    if sys.version_info >= (3, 8):
+        from .unix_events import MultiLoopChildWatcher as MultiLoopChildWatcher, ThreadedChildWatcher as ThreadedChildWatcher
 
 if sys.version_info >= (3, 8):
     from asyncio.exceptions import (

stdlib/3/asyncio/events.pyi

@@ -7,6 +7,8 @@ from asyncio.futures import Future
 from asyncio.protocols import BaseProtocol
 from asyncio.tasks import Task
 from asyncio.transports import BaseTransport
+from asyncio.unix_events import AbstractChildWatcher
+
 from _types import FileDescriptorLike
 
 _T = TypeVar('_T')
@@ -310,9 +312,9 @@ class AbstractEventLoopPolicy(metaclass=ABCMeta):
     def new_event_loop(self) -> AbstractEventLoop: ...
     # Child processes handling (Unix only).
     @abstractmethod
-    def get_child_watcher(self) -> Any: ...  # TODO: unix_events.AbstractChildWatcher
+    def get_child_watcher(self) -> AbstractChildWatcher: ...
     @abstractmethod
-    def set_child_watcher(self, watcher: Any) -> None: ...  # TODO: unix_events.AbstractChildWatcher
+    def set_child_watcher(self, watcher: AbstractChildWatcher) -> None: ...
 
 class BaseDefaultEventLoopPolicy(AbstractEventLoopPolicy, metaclass=ABCMeta):
     def __init__(self) -> None: ...
@@ -327,8 +329,8 @@ def get_event_loop() -> AbstractEventLoop: ...
 def set_event_loop(loop: Optional[AbstractEventLoop]) -> None: ...
 def new_event_loop() -> AbstractEventLoop: ...
 
-def get_child_watcher() -> Any: ...  # TODO: unix_events.AbstractChildWatcher
-def set_child_watcher(watcher: Any) -> None: ...  # TODO: unix_events.AbstractChildWatcher
+def get_child_watcher() -> AbstractChildWatcher: ...
+def set_child_watcher(watcher: AbstractChildWatcher) -> None: ...
 
 def _set_running_loop(loop: Optional[AbstractEventLoop]) -> None: ...
 def _get_running_loop() -> AbstractEventLoop: ...

stdlib/3/asyncio/selector_events.pyi

@@ -13,7 +13,7 @@ else:
 
 class BaseSelectorEventLoop(base_events.BaseEventLoop):
 
-    def __init__(self, selector: selectors.BaseSelector = ...) -> None: ...
+    def __init__(self, selector: Optional[selectors.BaseSelector] = ...) -> None: ...
     if sys.version_info >= (3, 7):
         async def create_unix_connection(
             self,

stdlib/3/asyncio/unix_events.pyi

@@ -0,0 +1,57 @@
+import sys
+import types
+from typing import Any, Callable, Optional, Type, TypeVar
+
+from .events import AbstractEventLoop, BaseDefaultEventLoopPolicy
+from .selector_events import BaseSelectorEventLoop
+
+_T1 = TypeVar('_T1', bound=AbstractChildWatcher)
+_T2 = TypeVar('_T2', bound=SafeChildWatcher)
+_T3 = TypeVar('_T3', bound=FastChildWatcher)
+
+class AbstractChildWatcher:
+    def add_child_handler(self, pid: int, callback: Callable[..., Any], *args: Any) -> None: ...
+    def remove_child_handler(self, pid: int) -> None: ...
+    def attach_loop(self, loop: Optional[AbstractEventLoop]) -> None: ...
+    def close(self) -> None: ...
+    def __enter__(self: _T1) -> _T1: ...
+    def __exit__(
+        self, typ: Optional[Type[BaseException]], exc: Optional[BaseException], tb: Optional[types.TracebackType]
+    ) -> None: ...
+    if sys.version_info >= (3, 8):
+        def is_active(self) -> bool: ...
+
+class BaseChildWatcher(AbstractChildWatcher):
+    def __init__(self) -> None: ...
+
+class SafeChildWatcher(BaseChildWatcher):
+    def __enter__(self: _T2) -> _T2: ...
+
+class FastChildWatcher(BaseChildWatcher):
+    def __enter__(self: _T3) -> _T3: ...
+
+class _UnixSelectorEventLoop(BaseSelectorEventLoop): ...
+
+class _UnixDefaultEventLoopPolicy(BaseDefaultEventLoopPolicy):
+    def get_child_watcher(self) -> AbstractChildWatcher: ...
+    def set_child_watcher(self, watcher: Optional[AbstractChildWatcher]) -> None: ...
+
+SelectorEventLoop = _UnixSelectorEventLoop
+
+DefaultEventLoopPolicy = _UnixDefaultEventLoopPolicy
+
+if sys.version_info >= (3, 8):
+
+    from typing import Protocol
+
+    _T4 = TypeVar('_T4', bound=MultiLoopChildWatcher)
+    _T5 = TypeVar('_T5', bound=ThreadedChildWatcher)
+    class _Warn(Protocol):
+        def __call__(
+            self, message: str, category: Optional[Type[Warning]] = ..., stacklevel: int = ..., source: Optional[Any] = ...
+        ) -> None: ...
+    class MultiLoopChildWatcher(AbstractChildWatcher):
+        def __enter__(self: _T4) -> _T4: ...
+    class ThreadedChildWatcher(AbstractChildWatcher):
+        def __enter__(self: _T5) -> _T5: ...
+        def __del__(self, _warn: _Warn = ...) -> None: ...