test

tidal_dl_ng/helper/decorator.py

@@ -0,0 +1,22 @@
+from typing import ClassVar
+
+
+class SingletonMeta(type):
+    """
+    The Singleton class can be implemented in different ways in Python. Some
+    possible methods include: base class, decorator, metaclass. We will use the
+    metaclass because it is best suited for this purpose.
+    """
+
+    _instances: ClassVar[dict] = {}
+
+    def __call__(cls, *args, **kwargs):
+        """
+        Possible changes to the value of the `__init__` argument do not affect
+        the returned instance.
+        """
+        if cls not in cls._instances:
+            instance = super().__call__(*args, **kwargs)
+            cls._instances[cls] = instance
+
+        return cls._instances[cls]