refactor(utils/bec_dispatcher): new singleton definition

bec_widgets/utils/bec_dispatcher.py

@@ -31,10 +31,22 @@ class _Connection:
         self.signal: pyqtSignal = self._signal_container.signal
 
 
-class _BECDispatcher(QObject):
+class BECDispatcher(QObject):
     """Utility class to keep track of slots connected to a particular redis connector"""
 
+    _instance = None
+    _initialized = False
+
+    def __new__(cls, client=None, *args, **kwargs):
+        if cls._instance is None:
+            cls._instance = super(BECDispatcher, cls).__new__(cls)
+            cls._initialized = False
+        return cls._instance
+
     def __init__(self, client=None):
+        if self._initialized:
+            return
+
         super().__init__()
         self.client = BECClient() if client is None else client
         try:
@@ -44,6 +56,13 @@ class _BECDispatcher(QObject):
 
         self._connections = {}
 
+        self._initialized = True
+
+    @classmethod
+    def reset_singleton(cls):
+        cls._instance = None
+        cls._initialized = False
+
     def connect_slot(
         self,
         slot: Callable,
@@ -170,18 +189,3 @@ class _BECDispatcher(QObject):
         for key, connection in list(self._connections.items()):
             for slot in list(connection.slots):
                 self._disconnect_slot_from_topic(slot, key)
-
-
-# variable holding the Singleton instance of BECDispatcher
-_bec_dispatcher = None
-
-
-def BECDispatcher():
-    global _bec_dispatcher
-    if _bec_dispatcher is None:
-        parser = argparse.ArgumentParser()
-        parser.add_argument("--bec-client", default=None)
-        args, _ = parser.parse_known_args()
-
-        _bec_dispatcher = _BECDispatcher(args.bec_client)
-    return _bec_dispatcher

tests/conftest.py

@@ -33,4 +33,4 @@ def bec_dispatcher(threads_check):
     # clean BEC client
     bec_dispatcher.client.shutdown()
     # reinitialize singleton for next test
-    bec_dispatcher_module._bec_dispatcher = None
+    bec_dispatcher_module.BECDispatcher.reset_singleton()