Improve dispatcher typing

homeassistant/components/cast/const.py

@@ -1,4 +1,15 @@
 """Consts for Cast integration."""
+from __future__ import annotations
+
+from typing import TYPE_CHECKING
+
+from pychromecast.controllers.homeassistant import HomeAssistantController
+
+from homeassistant.helpers.dispatcher import SignalType
+
+if TYPE_CHECKING:
+    from .helpers import ChromecastInfo
+
 
 DOMAIN = "cast"
 
@@ -14,14 +25,16 @@
 
 # Dispatcher signal fired with a ChromecastInfo every time we discover a new
 # Chromecast or receive it through configuration
-SIGNAL_CAST_DISCOVERED = "cast_discovered"
+SIGNAL_CAST_DISCOVERED: SignalType[ChromecastInfo] = SignalType("cast_discovered")
 
 # Dispatcher signal fired with a ChromecastInfo every time a Chromecast is
 # removed
-SIGNAL_CAST_REMOVED = "cast_removed"
+SIGNAL_CAST_REMOVED: SignalType[ChromecastInfo] = SignalType("cast_removed")
 
 # Dispatcher signal fired when a Chromecast should show a Home Assistant Cast view.
-SIGNAL_HASS_CAST_SHOW_VIEW = "cast_show_view"
+SIGNAL_HASS_CAST_SHOW_VIEW: SignalType[
+    HomeAssistantController, str, str, str | None
+] = SignalType("cast_show_view")
 
 CONF_IGNORE_CEC = "ignore_cec"
 CONF_KNOWN_HOSTS = "known_hosts"

homeassistant/components/cloud/__init__.py

@@ -25,6 +25,7 @@
 from homeassistant.helpers.aiohttp_client import async_get_clientsession
 from homeassistant.helpers.discovery import async_load_platform
 from homeassistant.helpers.dispatcher import (
+    SignalType,
     async_dispatcher_connect,
     async_dispatcher_send,
 )
@@ -68,7 +69,9 @@
 SERVICE_REMOTE_CONNECT = "remote_connect"
 SERVICE_REMOTE_DISCONNECT = "remote_disconnect"
 
-SIGNAL_CLOUD_CONNECTION_STATE = "CLOUD_CONNECTION_STATE"
+SIGNAL_CLOUD_CONNECTION_STATE: SignalType[CloudConnectionState] = SignalType(
+    "CLOUD_CONNECTION_STATE"
+)
 
 STARTUP_REPAIR_DELAY = 1  # 1 hour
 

homeassistant/components/cloud/const.py

@@ -1,4 +1,10 @@
 """Constants for the cloud component."""
+from __future__ import annotations
+
+from typing import Any
+
+from homeassistant.helpers.dispatcher import SignalType
+
 DOMAIN = "cloud"
 DATA_PLATFORMS_SETUP = "cloud_platforms_setup"
 REQUEST_TIMEOUT = 10
@@ -64,6 +70,6 @@
 MODE_DEV = "development"
 MODE_PROD = "production"
 
-DISPATCHER_REMOTE_UPDATE = "cloud_remote_update"
+DISPATCHER_REMOTE_UPDATE: SignalType[Any] = SignalType("cloud_remote_update")
 
 STT_ENTITY_UNIQUE_ID = "cloud-speech-to-text"

homeassistant/helpers/dispatcher.py

@@ -2,30 +2,73 @@
 from __future__ import annotations
 
 from collections.abc import Callable, Coroutine
+from dataclasses import dataclass
 from functools import partial
 import logging
-from typing import Any
+from typing import Any, Generic, TypeVarTuple, overload
 
 from homeassistant.core import HassJob, HomeAssistant, callback
 from homeassistant.loader import bind_hass
 from homeassistant.util.async_ import run_callback_threadsafe
 from homeassistant.util.logging import catch_log_exception
 
+_Ts = TypeVarTuple("_Ts")
+
 _LOGGER = logging.getLogger(__name__)
 DATA_DISPATCHER = "dispatcher"
 
+
+@dataclass(frozen=True)
+class SignalType(Generic[*_Ts]):
+    """Generic string class for signal to improve typing."""
+
+    name: str
+
+    def __hash__(self) -> int:
+        """Return hash of name."""
+
+        return hash(self.name)
+
+    def __eq__(self, other: Any) -> bool:
+        """Check equality for dict keys to be compatible with str."""
+
+        if isinstance(other, str):
+            return self.name == other
+        if isinstance(other, SignalType):
+            return self.name == other.name
+        return False
+
+
 _DispatcherDataType = dict[
-    str,
+    SignalType[*_Ts] | str,
     dict[
-        Callable[..., Any],
+        Callable[[*_Ts], Any] | Callable[..., Any],
         HassJob[..., None | Coroutine[Any, Any, None]] | None,
     ],
 ]
 
 
+@overload
+@bind_hass
+def dispatcher_connect(
+    hass: HomeAssistant, signal: SignalType[*_Ts], target: Callable[[*_Ts], None]
+) -> Callable[[], None]:
+    ...
+
+
+@overload
 @bind_hass
 def dispatcher_connect(
     hass: HomeAssistant, signal: str, target: Callable[..., None]
+) -> Callable[[], None]:
+    ...
+
+
+@bind_hass  # type: ignore[misc]  # workaround; exclude typing of 2 overload in func def
+def dispatcher_connect(
+    hass: HomeAssistant,
+    signal: SignalType[*_Ts],
+    target: Callable[[*_Ts], None],
 ) -> Callable[[], None]:
     """Connect a callable function to a signal."""
     async_unsub = run_callback_threadsafe(
@@ -41,9 +84,9 @@
 
 @callback
 def _async_remove_dispatcher(
-    dispatchers: _DispatcherDataType,
-    signal: str,
-    target: Callable[..., Any],
+    dispatchers: _DispatcherDataType[*_Ts],
+    signal: SignalType[*_Ts] | str,
+    target: Callable[[*_Ts], Any] | Callable[..., Any],
 ) -> None:
     """Remove signal listener."""
     try:
@@ -59,10 +102,30 @@
         _LOGGER.warning("Unable to remove unknown dispatcher %s", target)
 
 
+@overload
+@callback
+@bind_hass
+def async_dispatcher_connect(
+    hass: HomeAssistant, signal: SignalType[*_Ts], target: Callable[[*_Ts], Any]
+) -> Callable[[], None]:
+    ...
+
+
+@overload
 @callback
 @bind_hass
 def async_dispatcher_connect(
     hass: HomeAssistant, signal: str, target: Callable[..., Any]
+) -> Callable[[], None]:
+    ...
+
+
+@callback
+@bind_hass
+def async_dispatcher_connect(
+    hass: HomeAssistant,
+    signal: SignalType[*_Ts] | str,
+    target: Callable[[*_Ts], Any] | Callable[..., Any],
 ) -> Callable[[], None]:
     """Connect a callable function to a signal.
 
@@ -71,7 +134,7 @@
     if DATA_DISPATCHER not in hass.data:
         hass.data[DATA_DISPATCHER] = {}
 
-    dispatchers: _DispatcherDataType = hass.data[DATA_DISPATCHER]
+    dispatchers: _DispatcherDataType[*_Ts] = hass.data[DATA_DISPATCHER]
 
     if signal not in dispatchers:
         dispatchers[signal] = {}
@@ -84,13 +147,29 @@
     return partial(_async_remove_dispatcher, dispatchers, signal, target)
 
 
+@overload
+@bind_hass
+def dispatcher_send(hass: HomeAssistant, signal: SignalType[*_Ts], *args: *_Ts) -> None:
+    ...
+
+
+@overload
 @bind_hass
 def dispatcher_send(hass: HomeAssistant, signal: str, *args: Any) -> None:
+    ...
+
+
+@bind_hass  # type: ignore[misc]  # workaround; exclude typing of 2 overload in func def
+def dispatcher_send(hass: HomeAssistant, signal: SignalType[*_Ts], *args: *_Ts) -> None:
     """Send signal and data."""
     hass.loop.call_soon_threadsafe(async_dispatcher_send, hass, signal, *args)
 
 
-def _format_err(signal: str, target: Callable[..., Any], *args: Any) -> str:
+def _format_err(
+    signal: SignalType[*_Ts] | str,
+    target: Callable[[*_Ts], Any] | Callable[..., Any],
+    *args: Any,
+) -> str:
     """Format error message."""
     return "Exception in {} when dispatching '{}': {}".format(
         # Functions wrapped in partial do not have a __name__
@@ -101,7 +180,7 @@
 
 
 def _generate_job(
-    signal: str, target: Callable[..., Any]
+    signal: SignalType[*_Ts] | str, target: Callable[[*_Ts], Any] | Callable[..., Any]
 ) -> HassJob[..., None | Coroutine[Any, Any, None]]:
     """Generate a HassJob for a signal and target."""
     return HassJob(
@@ -110,16 +189,34 @@
     )
 
 
+@overload
+@callback
+@bind_hass
+def async_dispatcher_send(
+    hass: HomeAssistant, signal: SignalType[*_Ts], *args: *_Ts
+) -> None:
+    ...
+
+
+@overload
 @callback
 @bind_hass
 def async_dispatcher_send(hass: HomeAssistant, signal: str, *args: Any) -> None:
+    ...
+
+
+@callback
+@bind_hass
+def async_dispatcher_send(
+    hass: HomeAssistant, signal: SignalType[*_Ts] | str, *args: *_Ts
+) -> None:
     """Send signal and data.
 
     This method must be run in the event loop.
     """
     if (maybe_dispatchers := hass.data.get(DATA_DISPATCHER)) is None:
         return
-    dispatchers: _DispatcherDataType = maybe_dispatchers
+    dispatchers: _DispatcherDataType[*_Ts] = maybe_dispatchers
     if (target_list := dispatchers.get(signal)) is None:
         return
 

tests/helpers/test_dispatcher.py

@@ -5,6 +5,7 @@
 
 from homeassistant.core import HomeAssistant, callback
 from homeassistant.helpers.dispatcher import (
+    SignalType,
     async_dispatcher_connect,
     async_dispatcher_send,
 )
@@ -30,6 +31,32 @@ def test_funct(data):
     assert calls == [3, "bla"]
 
 
+async def test_signal_type(hass: HomeAssistant) -> None:
+    """Test dispatcher with SignalType."""
+    signal: SignalType[str, int] = SignalType("test")
+    calls: list[tuple[str, int]] = []
+
+    def test_funct(data1: str, data2: int) -> None:
+        calls.append((data1, data2))
+
+    async_dispatcher_connect(hass, signal, test_funct)
+    async_dispatcher_send(hass, signal, "Hello", 2)
+    await hass.async_block_till_done()
+
+    assert calls == [("Hello", 2)]
+
+    async_dispatcher_send(hass, signal, "World", 3)
+    await hass.async_block_till_done()
+
+    assert calls == [("Hello", 2), ("World", 3)]
+
+    # Test compatibility with string keys
+    async_dispatcher_send(hass, "test", "x", 4)
+    await hass.async_block_till_done()
+
+    assert calls == [("Hello", 2), ("World", 3), ("x", 4)]
+
+
 async def test_simple_function_unsub(hass: HomeAssistant) -> None:
     """Test simple function (executor) and unsub."""
     calls1 = []