What are some real-world examples of the Liskov Substitution Principle?

What are some real-world examples of the Liskov Substitution Principle?

The Liskov Substitution Principle (LSP) states that objects of a superclass should be replaceable with objects of a subclass without affecting the correctness of the program. A real-world example is a class hierarchy for shapes. If you have a superclass Shape and subclasses Circle and Square, you should be able to use a Circle wherever a Shape is expected.

Can you give me another example?

Sure! Consider a class Bird with a subclass Penguin. If you have a method that expects a Bird to fly, substituting a Penguin would violate LSP since penguins can't fly. Instead, you might create an interface FlyingBird for birds that can fly.

What about in software design?

In software design, think of a payment processing system. If you have a base class PaymentMethod and subclasses like CreditCard and PayPal, you should be able to use any subclass interchangeably in the payment processing function without issues.

How can I ensure my code follows LSP?

To ensure your code follows LSP, always design your subclasses to be substitutable for their base classes. This means they should adhere to the expected behavior of the base class and not introduce unexpected side effects.