some new features

.venv/lib/python3.12/site-packages/openpyxl/compat/singleton.py

@@ -0,0 +1,40 @@
+# Copyright (c) 2010-2024 openpyxl
+
+import weakref
+
+
+class Singleton(type):
+    """
+    Singleton metaclass
+    Based on Python Cookbook 3rd Edition Recipe 9.13
+    Only one instance of a class can exist. Does not work with __slots__
+    """
+
+    def __init__(self, *args, **kw):
+        super().__init__(*args, **kw)
+        self.__instance = None
+
+    def __call__(self, *args, **kw):
+        if self.__instance is None:
+            self.__instance = super().__call__(*args, **kw)
+        return self.__instance
+
+
+class Cached(type):
+    """
+    Caching metaclass
+    Child classes will only create new instances of themselves if
+    one doesn't already exist. Does not work with __slots__
+    """
+
+    def __init__(self, *args, **kw):
+        super().__init__(*args, **kw)
+        self.__cache = weakref.WeakValueDictionary()
+
+    def __call__(self, *args):
+        if args in self.__cache:
+            return self.__cache[args]
+
+        obj = super().__call__(*args)
+        self.__cache[args] = obj
+        return obj