Method overriding in Python - Step-by-Step Execution

Concept Flow - Method overriding

Define Parent class with method

↓

Define Child class overriding method

↓

Create Child object

↓

Call method on Child object

↓

Child's method runs, not Parent's

↓

End

This flow shows how a child class replaces a parent's method with its own when called on a child object.

Execution Sample

Python

class Parent:
    def greet(self):
        print("Hello from Parent")

class Child(Parent):
    def greet(self):
        print("Hello from Child")

c = Child()
c.greet()

This code shows a child class overriding a method from its parent and calling the child's version.

Execution Table

Step	Action	Evaluation	Output
1	Define class Parent with method greet	Parent.greet defined
2	Define class Child overriding greet	Child.greet defined
3	Create object c of class Child	c is Child instance
4	Call c.greet()	Calls Child.greet	Hello from Child
5	End of execution	No more code

💡 Program ends after calling overridden method on Child instance

Variable Tracker

Variable	Start	After Step 3	Final
c	undefined	Child instance created	Child instance

Key Moments - 2 Insights

Why does calling c.greet() run Child's method, not Parent's?

Because c is an instance of Child, and Child has its own greet method that overrides Parent's. See execution_table step 4 where Child.greet is called.

What if Child did not have greet method?

Then calling c.greet() would run Parent's greet method, since Child inherits it. This is shown by the absence of Child.greet in step 2.

Visual Quiz - 3 Questions

Look at the execution table, what is printed at step 4?

A "Hello from Parent"

B "Hello from Child"

C Nothing is printed

D Error occurs

💡 Hint

Check the Output column at step 4 in execution_table

At which step is the Child object created?

A Step 3

B Step 2

C Step 1

D Step 4

💡 Hint

Look at the Action column describing object creation in execution_table

If Child did not override greet, what would c.greet() call?

A No method found error

B Child.greet

C Parent.greet

D It would call a random method

💡 Hint

Refer to key_moments answer about inheritance when method is not overridden

Concept Snapshot

Method overriding lets a child class replace a parent's method.
Syntax: define method with same name in child class.
When called on child object, child's method runs.
If child lacks method, parent's runs.
Used to customize behavior in subclasses.

Full Transcript

Method overriding happens when a child class defines a method with the same name as one in its parent class. When you create an object of the child class and call that method, the child's version runs instead of the parent's. In the example, the Parent class has a greet method that prints 'Hello from Parent'. The Child class overrides greet to print 'Hello from Child'. When we create a Child object and call greet, it prints the child's message. This shows how overriding changes behavior in subclasses. If the child did not override greet, calling greet on the child object would run the parent's method instead.