__enter__

__getattr__
__next__

Author: ericksonlopes

class/example__enter__.py

@@ -0,0 +1,14 @@
+class Conn:
+    def __init__(self):
+        print('Connecting...')
+
+    def __enter__(self):
+        print('Connected to internet!')
+        return self
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        print('Disconnected...')
+
+
+with Conn() as conn:
+    print('Processing...')

class/example__getattr__.py

@@ -0,0 +1,24 @@
+class Main:
+    def __getattr__(self, attr):
+        setattr(self, attr, "default")
+        return attr
+
+
+class SeekAttr(Main):
+    def __getattr__(self, attr):
+        return super().__getattr__(attr)
+
+
+if __name__ == '__main__':
+    master = Main()
+
+    master.name = "John"
+    master.size = 100
+
+    print(master.name, master.size)
+
+    seek = SeekAttr()
+    seek.name = "Maria"
+    seek.size = 200
+
+    print(seek.name, seek.size)

class/example__next__.py

@@ -0,0 +1,25 @@
+class Connection:
+    __instance = None
+
+    def __new__(cls, *args, **kwargs):
+        if cls.__instance is None:
+            print('Connecting...')
+            cls.__instance = super().__new__(cls)
+            return cls.__instance
+        else:
+            print("Warning: There\'s already a connection!")
+            return cls.__instance
+
+    def __init__(self):
+        print('Connected to internet!')
+
+    def __del__(self):
+        print('Disconnected...')
+
+
+connection = Connection()
+
+connection2 = Connection()
+
+connection3 = Connection()
+