✨ add initial signals class definitions

sanic/signals.py

@@ -0,0 +1,43 @@
+from aiosignal import Signal
+from typing import Dict, List
+from sanic.request import Request
+from sanic.response import HTTPResponse
+
+
+class SignalData:
+    __slots__ = (
+        "context", "exception", "additional_info", "request", "response", "namespace",  "name"
+    )
+
+    def __init__(self, context, exception=None, request=None, response=None, additional_info=None):
+        self.context: str = context
+        self.exception: Exception = exception
+        self.additional_info: dict = additional_info
+        self.request: Request = request
+        self.response: HTTPResponse = response
+
+
+class Namespace:
+    def __init__(self, namespace):
+        self._namespace = namespace  # type: str
+        self._signals: Dict[str, Signal] = {}
+
+    def signal(self, name, owner):
+        try:
+            self._signals[name].append(Signal(owner=owner))
+        except KeyError:
+            self._signals[name] = Signal(owner=owner)
+
+    def register(self, name, callback):
+        self._signals[name].append(callback)
+
+    async def publish(self, name, data: SignalData = None):
+        if not data:
+            data = {}
+        data.namespace = self._namespace
+        data.name = name
+        await self._signals[name].send(data=data)
+
+    def freeze(self):
+        for key, signal in self._signals.items():
+            signal.freeze()