Codes

sessions/700.design-patterns-in-depth/725.singleton/740.code_example.py

@@ -0,0 +1,25 @@
+class SingletonMeta(type):
+
+    _instance = None
+    def __call__(self, *args, **kwargs):
+        if self._instance is None:
+            self._instance = super().__call__()
+        return self._instance
+
+class Singleton(metaclass=SingletonMeta):
+
+    def some_logic(self):
+        pass
+
+
+
+if __name__ == "__main__":
+
+    s1 = Singleton()
+    s2 = Singleton()
+
+    if id(s1) == id(s2):
+        print('Singleton works')
+    else:
+        print('singleton failed')
+