Object initialization flow in Python - Step-by-Step Execution

Concept Flow - Object initialization flow

Start: Create object

↓

Call __new__ method

↓

Allocate memory for object

↓

Call __init__ method

↓

Initialize attributes

↓

Object ready to use

↓

End

This flow shows how Python creates an object: first __new__ allocates memory, then __init__ sets up attributes.

Execution Sample

Python

class Dog:
    def __init__(self, name):
        self.name = name

d = Dog("Buddy")
print(d.name)

This code creates a Dog object named Buddy and prints its name.

Execution Table

Step	Action	Method Called	Attributes Set	Output
1	Start object creation	None	None	None
2	Call __new__	__new__	None	New Dog object allocated
3	Call __init__ with name='Buddy'	__init__	self.name = 'Buddy'	None
4	Object fully initialized	None	self.name = 'Buddy'	None
5	Print attribute	None	None	Buddy

💡 Object created and initialized; program prints the name attribute.

Variable Tracker

Variable	Start	After __new__	After __init__	Final
d	None	Dog object (empty)	Dog object with name='Buddy'	Dog object with name='Buddy'
self.name	None	None	'Buddy'	'Buddy'

Key Moments - 3 Insights

Why do we see __new__ before __init__ in the flow?

Because __new__ creates the object in memory first, then __init__ sets its attributes, as shown in steps 2 and 3 of the execution_table.

What happens if __init__ does not set any attributes?

The object is created but may have no useful data; step 3 would show __init__ called but no attributes set, so the object is empty.

Why does printing d.name show 'Buddy'?

Because __init__ assigned 'Buddy' to self.name (step 3), so the object stores this value and print outputs it (step 5).

Visual Quiz - 3 Questions

Look at the execution_table, what method is called right after starting object creation?

A __init__

B print

C __new__

D None

💡 Hint

Check step 2 in the execution_table where __new__ is called after starting.

At which step is the attribute 'name' set on the object?

A Step 2

B Step 3

C Step 4

D Step 5

💡 Hint

Look at the Attributes Set column in the execution_table for step 3.

If __init__ did not set self.name, what would print(d.name) output?

A AttributeError

B None

C 'Buddy'

D Empty string

💡 Hint

Refer to variable_tracker and key_moments about attribute assignment and access.

Concept Snapshot

Object creation in Python:
1. __new__ allocates memory for the object.
2. __init__ initializes object attributes.
3. __init__ runs after __new__.
4. Object is ready after __init__ finishes.
5. Access attributes like obj.attr after initialization.

Full Transcript

This visual trace shows how Python creates and initializes an object. First, the __new__ method is called to allocate memory for the new object. Then, the __init__ method runs to set up the object's attributes, like assigning a name. After __init__ finishes, the object is ready to use. For example, creating a Dog object with name 'Buddy' stores that name inside the object. Printing d.name then outputs 'Buddy'. This step-by-step flow helps understand the order and purpose of __new__ and __init__ in object initialization.