Factory Pattern

Factory Pattern

Here we are going to learn factory pattern in python suing a very simple example, 

@classmethod - is executed to determine the exact class to be invoked , as in the current scenario, the different switches might have different methods apart from the common method on each device.

The parent class @classmethod is going to determine the right Class , to be in instantiated for the requested devices type.

class Device(object):

@classmethod

def determine_type(cls, type_, *args, **kwargs):

return eval(type_)(*args, **kwargs)

def __init__(self, *args, **kwargs):

self.hostname = kwargs.get("hostname", "localhost")

self.username = kwargs.get("username", "admin")

def __str__(self):

return f"{self.__class__.__name__}:{self.username}@{self.hostname}"

class Cisco(Device):

def __init__(self, *args, **kwargs):

self.vendor = "Cisco"

super().__init__(*args, **kwargs)

class Brocade(Device):

def __init__(self, *args, **kwargs):

self.vendor = "Brocade"

super().__init__(*args, **kwargs)

if __name__ == "__main__":

obj = Device.determine_type(

"Cisco",

hostname="org.cisco.rnd.com",

username="superadmin")

obj1 = Device.determine_type("Brocade")

print(f"Device_1 = {obj}\nDevice_2 = {obj1}")

Output -- 

$python3 class_method.py

Device_1 = Cisco:superadmin@org.cisco.rnd.com

Device_2 = Brocade:admin@localhost

$ 

The static method is determining the correct class for the object by the device.