make run_in_thread return a Thread

ParamSpec is not fully supported in mypy yet though.
Hence, the type: ignore comment.

Author: rmorshea

requirements/pkg-deps.txt

@@ -1,4 +1,4 @@
-typing-extensions >=3.7.4
+typing-extensions >=3.10
 mypy-extensions >=0.4.3
 anyio >=3.0
 jsonpatch >=1.26

src/idom/server/proto.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+from threading import Thread
 from typing import Optional, TypeVar
 
 from typing_extensions import Protocol
@@ -32,7 +33,7 @@ class Server(Protocol[_App]):
     def run(self, host: str, port: int) -> None:
         """Start running the server"""
 
-    def run_in_thread(self, host: str, port: int) -> None:
+    def run_in_thread(self, host: str, port: int) -> Thread:
         """Run the server in a thread"""
 
     def wait_until_started(self, timeout: Optional[float] = None) -> None:

src/idom/server/utils.py

@@ -6,7 +6,9 @@
 from pathlib import Path
 from socket import socket
 from threading import Event, Thread
-from typing import Any, Callable, List, Optional, TypeVar, cast
+from typing import Any, Callable, List, Optional
+
+from typing_extensions import ParamSpec
 
 import idom
 
@@ -22,21 +24,23 @@
     "tornado",
 ]
 
-_Func = TypeVar("_Func", bound=Callable[..., None])
+
+_FuncParams = ParamSpec("_FuncParams")
 
 
-def threaded(function: _Func) -> _Func:
+def threaded(function: Callable[_FuncParams, None]) -> Callable[_FuncParams, Thread]:  # type: ignore
     @wraps(function)
-    def wrapper(*args: Any, **kwargs: Any) -> None:
+    def wrapper(*args: Any, **kwargs: Any) -> Thread:
         def target() -> None:
             asyncio.set_event_loop(asyncio.new_event_loop())
             function(*args, **kwargs)
 
-        Thread(target=target, daemon=True).start()
+        thread = Thread(target=target, daemon=True)
+        thread.start()
 
-        return None
+        return thread
 
-    return cast(_Func, wrapper)
+    return wrapper
 
 
 def wait_on_event(description: str, event: Event, timeout: Optional[float]) -> None: