Merge pull request mouredev#4434 from Jesusway69/main

mouredev#23 - Python

Roadmap/23 - SINGLETON/python/JesusWay69.py

@@ -0,0 +1,94 @@
+import os, platform
+from importlib import reload 
+
+if (platform.platform().startswith("macOS") or platform.platform().startswith("Linux")):
+    os.system('clear')
+else:
+    os.system('cls')
+
+
+""" * EJERCICIO:
+ * Explora el patrón de diseño "singleton" y muestra cómo crearlo
+ * con un ejemplo genérico.
+ *
+"""
+
+
+class SingletonMeta(type):
+
+    _instances = {}
+
+    def __call__(cls, *args, **kwargs):
+
+        if cls not in cls._instances:
+            instance = super().__call__(*args, **kwargs)
+            cls._instances[cls] = instance
+        return cls._instances[cls]
+
+class Singleton1(metaclass=SingletonMeta):
+    def print_logic(self):
+     print("Creando objeto..", self)
+
+if __name__ == "__main__":
+        Singleton1().print_logic()
+        instance1 = Singleton1()
+        instance2 = Singleton1()
+        print ("Instancia 1 = ", instance1)
+        print ("Instancia 2 = ", instance2)
+        print("\n")
+
+
+""" * DIFICULTAD EXTRA (opcional):
+ * Utiliza el patrón de diseño "singleton" para representar una clase que
+ * haga referencia a la sesión de usuario de una aplicación ficticia.
+ * La sesión debe permitir asignar un usuario (id, username, nombre y email),
+ * recuperar los datos del usuario y borrar los datos de la sesión."""
+
+
+def singleton (class_instance):
+    instances = {}
+    def get_instance(*args, **kwargs):
+        if class_instance == None:
+            instances.clear()
+            instances[class_instance] = class_instance(*args, **kwargs)
+            return instances[class_instance]
+        if class_instance not in instances:
+            instances[class_instance] = class_instance(*args, **kwargs)
+            return instances[class_instance]
+        if class_instance in instances:
+            return instances[class_instance]
+
+    return get_instance
+
+def singleton_off(singleton:singleton):
+    singleton = None
+    Session(singleton)
+    return singleton
+
+@singleton
+class Session:
+    def __init__(self,id=None,username=None,name=None,email=None):
+            self.id = id
+            self.username = username
+            self.name = name
+            self.email = email
+    def setter(self,id=None,username=None,name=None,email=None):
+            self.id = id
+            self.username = username
+            self.name = name
+            self.email = email
+
+jesus = Session(1, "Jesusway69", "Jesus", "[email protected]")
+jose = Session(2, "Pepe84", "Jose", "[email protected]")
+print(f"Jesus = id: {jesus.id}, username: {jesus.username}, name: {jesus.name}, email: {jesus.email}")
+print(f"Jose = id: {jose.id}, username: {jose.username}, name: {jose.name}, email: {jose.email}")
+print("Sesión de jesus: ", jesus)
+print("Sesión de jose: ", jose)
+jesus = singleton_off(jesus)
+print("Eliminando sesión de jesus...")
+print("Sesión de jesus: ", jesus)
+jesus = singleton(jesus)
+print("Nueva sesión de jesus: ", jesus)
+ana = Session()
+ana.setter(3, "Ana57", "Ana", "[email protected]")
+print(f"Ana = id:{ana.id}, username: {ana.username}, name: {ana.name}, email: {ana.email}, sesión singleton: {ana}")