refactor: emit content and metadata from messages in connect_slot

bec_widgets/bec_dispatcher.py

@@ -3,6 +3,7 @@ import itertools
 import os
 from dataclasses import dataclass
 from threading import RLock
+from typing import Callable
 
 from bec_lib import BECClient
 from bec_lib.core import BECMessage, MessageEndpoints, ServiceConfig
@@ -57,10 +58,7 @@ class _BECDispatcher(QObject):
 
         self.client.initialize(config=ServiceConfig(config_path=bec_config))
 
-        self._slot_signal_map = {
+        self._slot_signal_map = {"on_scan_segment": self.scan_segment, "on_new_scan": self.new_scan}
-            "on_scan_segment": self.scan_segment,
-            "on_new_scan": self.new_scan,
-        }
         self._daps = {}
         self._connections = {}
 
@@ -81,8 +79,7 @@ class _BECDispatcher(QObject):
 
         scan_segment_topic = MessageEndpoints.scan_segment()
         self._scan_segment_thread = self.client.connector.consumer(
-            topics=scan_segment_topic,
+            topics=scan_segment_topic, cb=_scan_segment_cb
-            cb=_scan_segment_cb,
         )
         self._scan_segment_thread.start()
 
@@ -92,12 +89,22 @@ class _BECDispatcher(QObject):
             if callable(slot):
                 signal.connect(slot)
 
-    def connect_slot(self, slot, topic):
+    def connect_slot(self, slot: Callable, topic: str) -> None:
+        """Connect widget's pyqt slot, so that it is called on new pub/sub topic message
+
+        Args:
+            slot (Callable): A slot method/function that accepts two inputs: content and metadata of
+                the corresponding pub/sub message
+            topic (str): A topic that can typically be acquired via bec_lib.core.MessageEndpoints
+        """
         # create new connection for topic if it doesn't exist
         if topic not in self._connections:
 
             def cb(msg):
                 msg = BECMessage.MessageReader.loads(msg.value)
+                # TODO: this can could be replaced with a simple
+                # self._connections[topic].signal.emit(msg.content, msg.metadata)
+                # once all dispatcher.connect_slot calls are made with a single topic only
                 if not isinstance(msg, list):
                     msg = [msg]
                 for msg_i in msg:
@@ -113,7 +120,14 @@ class _BECDispatcher(QObject):
             self._connections[topic].signal.connect(slot)
             self._connections[topic].slots.add(slot)
 
-    def disconnect_slot(self, slot, topic):
+    def disconnect_slot(self, slot: Callable, topic: str) -> None:
+        """Disconnect widget's pyqt slot from pub/sub updates on a topic.
+
+        Args:
+            slot (Callable): A slot to be disconnected
+            topic (str): A corresponding topic that can typically be acquired via
+                bec_lib.core.MessageEndpoints
+        """
         if topic not in self._connections:
             return