Is the Classes & Objects lesson free?

The interactive Classes & Objects lesson is part of Pro (₹299/month). The first 5 lessons of the track are free — no account or card needed.

How long does the Classes & Objects lesson take?

About 10 minutes end-to-end. It's a hands-on lesson — you read a paragraph, edit the code, and run it in the same tab.

Do I need to install Python to try the Classes & Objects lesson?

No install required. PyRun runs real CPython in your browser via Pyodide (Python compiled to WebAssembly). Works on Chrome, Firefox, Safari, and Edge — desktop or mobile.

What level is the Classes & Objects lesson?

Intermediate level. Best after finishing the Beginner track (syntax, control flow, functions, data types).

Classes & Objects

Intermediate
10 min
Fundamentals
intermediate · oop
Try it

Lesson 28 of 43

In this track

You’ll be able to

Define classes with class and initialize with __init__
Create instances and access instance attributes
Write instance methods that operate on self
Understand the difference between class and instance state

Why this matters

Every serious framework — Django models, SQLAlchemy declarative base, Pydantic BaseModel, PyTorch nn.Module — is class-based. Understanding self, __init__, and method resolution order is what separates script writers from library authors.

Common pitfalls

Mutable default arguments like def __init__(self, items=[]) — shared across instances; use None sentinel instead.
Forgetting self on method calls or attribute reads — Python won't warn; you'll get NameError at runtime.
Overriding __eq__ without __hash__ — silently breaks set and dict membership.

Intermediate · 5 minIn-memory I/ORead and write 'files' that live in memory — perfect for browser Python.Intermediate · 7 minRecursionFunctions that call themselves — and how to stay sane doing it.Intermediate · 7 minCounter, defaultdict, namedtupleThree power tools from the `collections` module.

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You’ll be able to

Define classes with class and initialize with __init__
Create instances and access instance attributes
Write instance methods that operate on self
Understand the difference between class and instance state

Why this matters

Common pitfalls

Mutable default arguments like def __init__(self, items=[]) — shared across instances; use None sentinel instead.
Forgetting self on method calls or attribute reads — Python won't warn; you'll get NameError at runtime.
Overriding __eq__ without __hash__ — silently breaks set and dict membership.

You’ll be able to

Why this matters

Common pitfalls

Related lessons

You’ll be able to

Why this matters

Common pitfalls

Related lessons