Merge pull request #4102 from hozlucas28/Solution-23-Python

#23 - Python

Author: Roswell468

Roadmap/23 - SINGLETON/python/hozlucas28.py

@@ -0,0 +1,143 @@
+# pylint: disable=pointless-string-statement,missing-class-docstring,missing-function-docstring
+
+"""
+    Singleton pattern...
+"""
+
+from typing import Any, Self
+
+
+print("Singleton pattern...")
+
+
+class SingletonMeta(type):
+    __instances: dict[Any, Any] = {}
+
+    def __call__(cls, *args: Any, **kwds: Any) -> Any:
+        if cls not in cls.__instances:
+            instance: Any = super().__call__(*args, **kwds)
+            cls.__instances[cls] = instance
+
+        return cls.__instances[cls]
+
+
+class Counter(metaclass=SingletonMeta):
+    def __init__(self) -> None:
+        self.__count: int = 0
+
+    def get_count(self) -> int:
+        return self.__count
+
+    def increment(self) -> Self:
+        self.__count += 1
+        return self
+
+    def decrement(self) -> Self:
+        self.__count -= 1
+        return self
+
+
+counter_01: Counter = Counter()
+counter_02: Counter = Counter()
+
+print(
+    "\nAre `counter_01` and `counter_02` the same instance of `Counter` class?"
+    + f" {counter_01 == counter_02}",
+)
+
+print("\nMethod call of `counter_01` instance...")
+
+counter_01.increment().increment().increment()
+print("\ncounter01.increment().increment().increment()")
+
+print(f"\nCount attribute of `counter_01` instance --> {counter_01.get_count()}")
+
+
+print("\nMethod call of `counter_02` instance...")
+
+counter_02.decrement()
+print("\ncounter02.decrement()")
+
+print(f"\nCount attribute of `counter_02` instance --> {counter_02.get_count()}")
+
+print(
+    "\n# ---------------------------------------------------------------------------------- #\n"
+)
+
+
+"""
+    Additional challenge...
+"""
+
+print("Additional challenge...")
+
+
+class UserSession(metaclass=SingletonMeta):
+    __email: str
+    __uid: str
+    __name: str
+    __user_name: str
+
+    def __init__(self, *, email="", uid="", name="", user_name="") -> None:
+        self.__email = email
+        self.__uid = uid
+        self.__name = name
+        self.__user_name = user_name
+
+    def get_email(self) -> str:
+        return self.__email
+
+    def get_uid(self) -> str:
+        return self.__uid
+
+    def get_name(self) -> str:
+        return self.__name
+
+    def get_user_name(self) -> str:
+        return self.__user_name
+
+    def set_email(self, new_email: str) -> Self:
+        self.__email = new_email
+        return self
+
+    def set_uid(self, new_uid: str) -> Self:
+        self.__uid = new_uid
+        return self
+
+    def set_name(self, new_name: str) -> Self:
+        self.__name = new_name
+        return self
+
+    def set_user_name(self, new_user_name: str) -> Self:
+        self.__user_name = new_user_name
+        return self
+
+    def delete_data(self) -> Self:
+        self.__email = ""
+        self.__uid = ""
+        self.__name = ""
+        self.__user_name = ""
+        return self
+
+
+user_session: UserSession = UserSession(
+    email="[email protected]",
+    name="Juan",
+    uid="15H4G-A5D-1Y7",
+    user_name="JuanGamer16",
+)
+
+print(
+    "\nUser: "
+    + f"{user_session.get_uid()} {user_session.get_name()} "
+    + f"{user_session.get_user_name()} {user_session.get_email()}"
+)
+
+user_session.delete_data()
+print("\nUser data deleted!")
+
+print(
+    "\nUser: "
+    + f"{user_session.get_uid()} {user_session.get_name()} "
+    + f"{user_session.get_user_name()} {user_session.get_email()}"
+)