Extending parent behavior in Python - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does it mean to extend parent behavior in Python classes?

It means adding new features or modifying existing ones in a child class while still using the behavior defined in the parent class.

beginner

How do you call a method from the parent class inside a child class in Python?

You use <code>super().method_name()</code> to call the parent class method from the child class.

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Why would you want to extend parent behavior instead of completely replacing it?

To keep the original functionality and add extra features or changes without losing what the parent class already does.

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Example: What will this code print?
<pre>class Parent:
    def greet(self):
        print('Hello from Parent')

class Child(Parent):
    def greet(self):
        super().greet()
        print('Hello from Child')

c = Child()
c.greet()</pre>

It will print: Hello from Parent Hello from Child Because the child calls the parent's greet method first, then adds its own message.

beginner

What happens if you forget to call super() when overriding a method?

The parent class method won't run, so you lose the original behavior and only the child's code runs.

What keyword is used to call a parent class method in Python?

A base()

B parent()

C self()

D super()

The super() function is used to access methods from the parent class.

If a child class overrides a method but does NOT call super(), what happens?

A Only child method runs

B Error occurs

C Both parent and child methods run automatically

D Parent method runs first

Without super(), only the child method runs, skipping the parent method.

Why use super() inside an overridden method?

A To call the parent class method and extend its behavior

B To call a method from another unrelated class

C To create a new method

D To delete the parent method

super() calls the parent method so you can add to it instead of replacing it.

What is the output of this code?

class A:
    def say(self):
        print('A')

class B(A):
    def say(self):
        print('B')
        super().say()

b = B()
b.say()

A A\nB

B A

C B\nA

D B

The child prints 'B' first, then calls the parent method which prints 'A'.

Extending parent behavior helps to:

A Completely replace parent code

B Reuse code and add new features

C Avoid using inheritance

D Make code slower

Extending behavior allows reuse of existing code while adding new functionality.

Explain how to extend a parent class method in Python and why it is useful.

Think about how to keep old behavior and add new steps.

Describe what happens if you override a method without calling super() in a child class.

Consider what part of the code is skipped.