Real-world modeling using objects in Python - Step-by-Step Execution

Concept Flow - Real-world modeling using objects

Define Class

↓

Create Object

↓

Set Attributes

↓

Call Methods

↓

Use Object Data

↓

End

We start by defining a class, then create an object from it, set its attributes, call its methods, and finally use the data stored in the object.

Execution Sample

Python

class Car:
    def __init__(self, make, year):
        self.make = make
        self.year = year
    def display(self):
        print(f"Car: {self.make}, Year: {self.year}")

my_car = Car('Toyota', 2020)
my_car.display()

This code defines a Car class, creates a car object with make and year, and prints its details.

Execution Table

Step	Action	Evaluation	Result
1	Define class Car	Class Car created	Car class ready to use
2	Create my_car = Car('Toyota', 2020)	Call __init__ with make='Toyota', year=2020	Object my_car created with attributes make='Toyota', year=2020
3	Call my_car.display()	Execute display method	Prints: Car: Toyota, Year: 2020
4	End of program	No more instructions	Program stops

💡 Program ends after displaying car details

Variable Tracker

Variable	Start	After Step 2	After Step 3	Final
my_car	None	Car object with make='Toyota', year=2020	Same object	Same object

Key Moments - 2 Insights

Why do we use self.make and self.year inside __init__?

self.make and self.year store the values inside the object so each object keeps its own data, as shown in step 2 of the execution_table.

What happens when we call my_car.display()?

The display method uses the object's stored data to print details, as seen in step 3 where it prints the car's make and year.

Visual Quiz - 3 Questions

Look at the execution_table, what is the value of my_car.make after step 2?

A 'Toyota'

B 'Car'

C 2020

D None

💡 Hint

Check variable_tracker row for my_car after step 2

At which step does the program print the car details?

A Step 2

B Step 3

C Step 1

D Step 4

💡 Hint

Look at the execution_table action and result columns

If we create another Car object with make='Honda' and year=2018, what changes in variable_tracker?

A my_car changes to Honda

B my_car.make becomes 2018

C A new variable with Honda and 2018 appears

D No changes

💡 Hint

Each object stores its own data separately, see variable_tracker for my_car

Concept Snapshot

class ClassName:
    def __init__(self, params):
        self.attr = value  # store data
    def method(self):
        # use self.attr
obj = ClassName(args)  # create object
obj.method()  # call method
Objects model real things with attributes and actions.

Full Transcript

This example shows how to model a real-world object using Python classes. We define a Car class with attributes make and year. When we create an object my_car, the __init__ method sets these attributes. Calling my_car.display() prints the car's details. Variables inside the object keep their own data using self. The execution table traces each step: defining the class, creating the object, calling the method, and ending the program. The variable tracker shows how my_car holds its data after creation. Key moments clarify why self is used and what happens when methods are called. The quiz tests understanding of object attributes and method calls. This approach helps beginners see how code runs step-by-step to model real things with objects.