Type fixes (#629)

- Add dependency on typing extensions to we can use param specifiers for wrapper functions
- Fix for typing of aliased functions
- Fix for typing of synchronized functions
- Fix type error in flat-map

.pre-commit-config.yaml

@@ -26,7 +26,7 @@ repos:
         language: node
         pass_filenames: false
         types: [python]
-        additional_dependencies: ["pyright@1.1.227"]
+        additional_dependencies: ["pyright@1.1.228"]
     repo: local
   - hooks:
       - id: mypy

examples/timeflies/timeflies_tkinter.py

@@ -38,10 +38,12 @@ def label2stream(
     def char2label(char: str) -> Label:
         return Label(frame, text=char)
 
-    reactivex.from_(text).pipe(
+    xs = reactivex.of(text).pipe(
         ops.map(char2label),
         ops.flat_map_indexed(label2stream),
-    ).subscribe(on_next, on_error=print, scheduler=scheduler)
+    )
+
+    xs.subscribe(on_next, on_error=print, scheduler=scheduler)
 
     frame.pack()
     root.mainloop()

pyproject.toml

@@ -29,6 +29,7 @@ packages = [
 
 [tool.poetry.dependencies]
 python = ">= 3.7, < 3.11"
+typing-extensions = "^4.1.1"
 
 [tool.poetry.dev-dependencies]
 pytest-asyncio = "^0.18.1"

reactivex/abc/observer.py

@@ -9,7 +9,7 @@
 OnCompleted = Callable[[], None]
 
 
-class ObserverBase(Generic[_T], ABC):
+class ObserverBase(Generic[_T_in], ABC):
     """Observer abstract base class
 
     An Observer is the entity that receives all emissions of a
@@ -19,7 +19,7 @@ class ObserverBase(Generic[_T], ABC):
     __slots__ = ()
 
     @abstractmethod
-    def on_next(self, value: _T) -> None:
+    def on_next(self, value: _T_in) -> None:
         """Notifies the observer of a new element in the sequence.
 
         Args:

reactivex/abc/scheduler.py

@@ -10,7 +10,8 @@
 RelativeTime = Union[timedelta, float]
 AbsoluteOrRelativeTime = Union[datetime, timedelta, float]
 ScheduledAction = Callable[
-    ["SchedulerBase", Optional[_TState]], Optional[DisposableBase]
+    ["SchedulerBase", Optional[_TState]],
+    Optional[DisposableBase],
 ]
 
 

reactivex/internal/concurrency.py

@@ -1,18 +1,23 @@
 from threading import RLock, Thread
-from typing import Any, Callable
+from typing import Any, Callable, TypeVar
+
+from typing_extensions import ParamSpec
 
 from reactivex.typing import StartableTarget
 
+_T = TypeVar("_T")
+_P = ParamSpec("_P")
+
 
 def default_thread_factory(target: StartableTarget) -> Thread:
     return Thread(target=target, daemon=True)
 
 
-def synchronized(lock: RLock) -> Callable[[Callable[..., Any]], Callable[..., Any]]:
+def synchronized(lock: RLock) -> Callable[[Callable[_P, _T]], Callable[_P, _T]]:
     """A decorator for synchronizing access to a given function."""
 
-    def wrapper(fn: Callable[..., Any]) -> Callable[..., Any]:
-        def inner(*args: Any, **kw: Any) -> Any:
+    def wrapper(fn: Callable[_P, _T]) -> Callable[_P, _T]:
+        def inner(*args: _P.args, **kw: _P.kwargs) -> Any:
             with lock:
                 return fn(*args, **kw)
 

reactivex/internal/utils.py

@@ -2,6 +2,8 @@
 from types import FunctionType
 from typing import TYPE_CHECKING, Any, Callable, Iterable, Optional, TypeVar, cast
 
+from typing_extensions import ParamSpec
+
 from reactivex import abc
 from reactivex.disposable import CompositeDisposable
 from reactivex.disposable.refcountdisposable import RefCountDisposable
@@ -10,6 +12,7 @@
     from reactivex import Observable
 
 _T = TypeVar("_T")
+_P = ParamSpec("_P")
 
 
 def add_ref(xs: "Observable[_T]", r: RefCountDisposable) -> "Observable[_T]":
@@ -30,7 +33,7 @@ def infinite() -> Iterable[int]:
         n += 1
 
 
-def alias(name: str, doc: str, fun: Callable[..., Any]) -> Callable[..., Any]:
+def alias(name: str, doc: str, fun: Callable[_P, _T]) -> Callable[_P, _T]:
     # Adapted from
     # https://stackoverflow.com/questions/13503079/how-to-create-a-copy-of-a-python-function#
     # See also help(type(lambda: 0))

reactivex/operators/_flatmap.py

@@ -1,8 +1,9 @@
 from asyncio import Future
-from typing import Any, Callable, Iterable, Optional, TypeVar, Union, cast
+from typing import Any, Callable, Optional, TypeVar, Union, cast
 
 from reactivex import Observable, from_, from_future
 from reactivex import operators as ops
+from reactivex.internal.basic import identity
 from reactivex.typing import Mapper, MapperIndexed
 
 _T1 = TypeVar("_T1")
@@ -14,14 +15,16 @@ def _flat_map_internal(
     mapper: Optional[Mapper[_T1, Any]] = None,
     mapper_indexed: Optional[MapperIndexed[_T1, Any]] = None,
 ) -> Observable[Any]:
-    def projection(x: _T1, i: int):
-        mapper_result = (
-            mapper(x) if mapper else mapper_indexed(x, i) if mapper_indexed else None
+    def projection(x: _T1, i: int) -> Observable[Any]:
+        mapper_result: Any = (
+            mapper(x)
+            if mapper
+            else mapper_indexed(x, i)
+            if mapper_indexed
+            else identity
         )
         if isinstance(mapper_result, Future):
             result: Observable[Any] = from_future(cast("Future[Any]", mapper_result))
-        elif isinstance(mapper_result, Iterable):
-            result = from_(mapper_result)
         elif isinstance(mapper_result, Observable):
             result = mapper_result
         else: