Question

Consider a class that represents a hardware device. The device can be in one of two states: plugged in or unplugged. Which of the following class definitions is best for this situation?

a) class HardwareDevice:
state = "Plugged In"

b) class HardwareDevice:
state = "Unplugged"

c) class HardwareDevice:
state = "Plugged In", "Unplugged"

d) class HardwareDevice:
state = None

Answer 1

The optimal class definition for a hardware device with two states, 'Plugged In' and 'Unplugged', is to have a state attribute initially set to None. This allows flexibility for each instance of the class to have its state set according to the actual status of the device, without assuming a default state.

Step-by-step explanation:

When considering a class that represents a hardware device with two possible states, it's important that the class is designed to efficiently handle the state changes. Considering the options provided, the best design choice would be:

d) class HardwareDevice: state = None

This approach initializes the state attribute to None, which is a common practice for variables that will be set to a meaningful value later. Since a hardware device can be either 'Plugged In' or 'Unplugged', assigning an initial state like 'Plugged In' or 'Unplugged' directly in the class definition may not be flexible enough for all instances of the class. Instead, the initial value of None signifies that the state has not been set yet and avoids the risk of incorrectly assuming a default state. Further implementation may include methods to set the state correctly according to actual device status.