More flexible and add deps for http+websockets server

yacv_server/events.py

@@ -0,0 +1,27 @@
+from typing import TypeVar, Generic, List, Callable
+
+T = TypeVar('T')
+
+
+class EventPublisher(Generic[T]):
+    """A buffered event publisher that broadcasts to all listeners, including all previously emitted data"""
+
+    _listeners: List[Callable[[T], None]]
+    _buffer: List[T]
+
+    def __init__(self):
+        self._listeners = []
+        self._buffer = []
+
+    def subscribe(self, listener: Callable[[T], None]):
+        self._listeners.append(listener)
+        for data in self._buffer:
+            listener(data)
+
+    def unsubscribe(self, listener: Callable[[T], None]):
+        self._listeners.remove(listener)
+
+    def emit(self, data: T):
+        self._buffer.append(data)
+        for listener in self._listeners:
+            listener(data)