adjust project content

pilot/singleton.py

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+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+"""The singleton metaclass for ensuring only one instance of a class."""
+import abc
+from typing import Any
+
+class Singleton(abc.ABCMeta, type):
+    """ Singleton metaclass for ensuring only one instance of a class"""
+
+    _instances = {}
+    def __call__(cls, *args: Any, **kwargs: Any) -> Any:
+        """Call method for the singleton metaclass"""
+        if cls not in cls._instances:
+            cls._instances[cls] = super(Singleton, cls).__call__(*args, **kwargs)
+        return cls._instances[cls]
+
+
+class AbstractSingleton(abc.ABC, metaclass=Singleton):
+    """Abstract singleton class for ensuring only one instance of a class"""
+    pass