How does a class method differ from an instance method?
PICTURE THIS: OOP PILLARS
Simple meaning
An instance method receives the instance as self and works with per-object state.
WHY — OOP instead of guessing?
Why interviewers care about OOP:
question about OOP.
trade-offs, and what you would actually do on a Python project - not buzzwords.
Name the idea, why it exists, then one short example.
End with when you use it and one common pitfall.
STEPS — What happens step by step?
Before you speak the answer, walk the interviewer through these steps:
- 1An instance method receives
the instance as self and works with per-object state.
- 2A class method is
marked with @classmethod and receives the class as cls, which is handy for alternate constructors.
- 3A static method receives
neither and is just a function namespaced on the class.
- 4Give an example
One tiny concrete case you can say aloud.
- 5Common mistake
What juniors usually get wrong.
- 6Close
When you pick this over the alternative.
EXAMPLE — See it in action
Here's a short line you can speak, broken into clear beats:
Note: Adapt this scaffold to your own project — keep it under 60–90 seconds.
Key takeaway
An instance method receives the instance as self and works with per-object state. A class method is marked with @classmethod and receives the class as cls, which is handy for alternate constructors.