Modifying object state in Python - Step-by-Step Execution

Concept Flow - Modifying object state

Create object

↓

Access object attribute

↓

Modify attribute value

↓

Use updated object state

↓

End

This flow shows how an object is created, its attribute accessed and modified, then used with the updated state.

Execution Sample

Python

class Car:
    def __init__(self, color):
        self.color = color

my_car = Car('red')
my_car.color = 'blue'
print(my_car.color)

This code creates a Car object with color 'red', changes its color to 'blue', then prints the updated color.

Execution Table

Step	Action	Object State (color)	Output
1	Create Car object with color 'red'	color='red'
2	Modify my_car.color to 'blue'	color='blue'
3	Print my_car.color	color='blue'	blue
4	End of program	color='blue'

💡 Program ends after printing the updated color attribute.

Variable Tracker

Variable	Start	After Step 1	After Step 2	Final
my_car.color	undefined	red	blue	blue

Key Moments - 2 Insights

Why does changing my_car.color affect the object state?

Because my_car.color refers to the attribute inside the object, modifying it updates the object's stored value as shown in step 2 of the execution_table.

Does creating the object set the attribute value?

Yes, in step 1 the __init__ method sets color='red', initializing the object's state.

Visual Quiz - 3 Questions

Look at the execution_table, what is the color attribute of my_car after step 1?

A 'red'

B 'blue'

C undefined

D 'green'

💡 Hint

Check the 'Object State (color)' column in row for step 1.

At which step does the color attribute change from 'red' to 'blue'?

A Step 1

B Step 3

C Step 2

D Step 4

💡 Hint

Look at the 'Action' and 'Object State' columns in the execution_table.

If we remove the line 'my_car.color = "blue"', what will be printed at step 3?

A 'blue'

B 'red'

C Error

D Nothing

💡 Hint

Refer to the initial attribute set in step 1 and the absence of modification in step 2.

Concept Snapshot

Modifying object state:
- Create object with attributes
- Access attribute via object.attribute
- Assign new value to attribute to update state
- Updated attribute reflects in later use
- Changes affect only that object instance

Full Transcript

This example shows how to change the state of an object in Python. First, we create a Car object with color set to 'red'. This sets the initial state. Then, we modify the color attribute to 'blue' by assigning a new value. Finally, when we print the color, it shows 'blue', confirming the state change. The execution table tracks each step and the object's color attribute. The variable tracker shows how my_car.color changes from undefined to 'red' then 'blue'. Key moments clarify why changing the attribute updates the object and how the initial value is set. The quiz tests understanding of when and how the attribute changes. This helps beginners see how object state is modified step-by-step.