Proxy Design Pattern in Python
Write a Python program to implement Proxy Design Pattern.
class Car: |
'''Resource-intensive object''' |
def driveCar(self): |
print("Driving Car....") |
|
class CarProxy: |
'''Relatively less resource-intensive proxy acting as middleman. Instantiates a Car object only if the driver is of age.''' |
def __init__(self): |
self.ageOfDriver = 15 |
self.car = None |
|
def driveCar(self): |
print("Proxy in action. Checking to see if the driver is of age or underage...") |
if self.ageOfDriver >= 18: |
# If driver is of age, let him drive the car. |
self.car = Car() |
self.car.driveCar() |
else: |
# Otherwise, don't instantiate the car object. |
print("Driver is underage. Can't drive the car.") |
|
# Instantiate the Proxy |
carProxy = CarProxy() |
# Client attempting to drive a car at the default age of 15. Logically, since he/she cannot have a driving license, there is no need to buy a car, or, in our case, make the car object. |
carProxy.driveCar() |
|
# OUTPUT: |
# Proxy in action. Checking to see if the driver is of age or underage... |
# Driver is underage. Can't drive the car. |
|
# Altering the age of the driver |
carProxy.ageOfDriver = 21 |
# Client attempting to drive a car at the default age of 21. Should succeed. |
carProxy.driveCar() |
|
# OUTPUT: |
# Proxy in action. Checking to see if the driver is of age or underage... |
# Driving Car.... |
See also:
- Python 101
- Object Oriented Python
- Design Patterns in Python
- 50+ Handy Standard Library Modules
- 60+ Handy Third Library Modules
- 50+ Tips & Tricks for Python Developers
- 50+ Know-How(s) Every Pythonista Must Know