initial

src/managers/decorators/singleton.py

@@ -0,0 +1,13 @@
+import threading
+
+def singleton(cls):
+    instances = {}
+    lock = threading.Lock()
+    
+    def get_instance(*args, **kwargs):
+        if cls not in instances:
+            with lock:
+                if cls not in instances:
+                    instances[cls] = cls(*args, **kwargs)
+        return instances[cls]
+    return get_instance