Python Developer interview question · Most asked
Explain mutable vs immutable in Python.
Summary
Mutable objects can change in place after creation; immutable objects cannot change their value once created.
Longer Answer
Lists, dictionaries, and sets are mutable, so aliases to the same object can observe changes made through any reference. Integers, strings, tuples, frozensets, and bytes are immutable, so operations create new objects or reuse existing immutable values.
This matters for default arguments, hashing, caching, defensive copying, and API design. A common bug is using a mutable default such as [] in a function signature, which is shared across calls.
Key Points
- Lists, dictionaries, and sets are mutable, so aliases to the same object can observe changes made through any reference
- Integers, strings, tuples, frozensets, and bytes are immutable, so operations create new objects or reuse existing immutable values
- This matters for default arguments, hashing, caching, defensive copying, and API design
- For 'Explain mutable vs immutable in Python.', a strong interview answer should define the mechanism, name the common failure mode, and explain the production decision it affects.
This matters for default arguments, hashing, caching, defensive copying, and API design. A common bug is using a mutable default such as [] in a function signature, which is shared across calls
Comparison / Tradeoffs
| Aspect | Notes |
|---|---|
| Core idea | Mutable objects can change in place after creation; immutable objects cannot change their value once created. |
| Practical tradeoff | For 'Explain mutable vs immutable in Python.', a strong interview answer should define the mechanism, name the common failure mode, and explain the production decision it affects. |
This matters for default arguments, hashing, caching, defensive copying, and API design. A common bug is using a mutable default such as [] in a function signature, which is shared across calls. |
Explanation
Summary
Mutable objects can change in place after creation; immutable objects cannot change their value once created.
Longer Answer
For 'Explain mutable vs immutable in Python.', a strong interview answer should define the mechanism, name the common failure mode, and explain the production decision it affects.
This matters for default arguments, hashing, caching, defensive copying, and API design. A common bug is using a mutable default such as [] in a function signature, which is shared across calls.
Key Points
- For 'Explain mutable vs immutable in Python.', a strong interview answer should define the mechanism, name the common failure mode, and explain the production decision it affects
- This matters for default arguments, hashing, caching, defensive copying, and API design
- A common bug is using a mutable default such as [] in a function signature, which is shared across calls
- Use the answer to connect the concept back to a realistic production or interview scenario for 'Explain mutable vs immutable in Python.'
Comparison / Tradeoffs
| Aspect | Notes |
|---|---|
| Core idea | Mutable objects can change in place after creation; immutable objects cannot change their value once created. |
| Practical tradeoff | For 'Explain mutable vs immutable in Python.', a strong interview answer should define the mechanism, name the common failure mode, and explain the production decision it affects. |
More most-asked Python Developer questions
- Backend Python interview: explain N+1 queries.
- Backend Python interview: explain authN vs authZ.
- Backend Python interview: explain SQL injection prevention.
- Explain decorators in Python.
- Explain context managers in Python.
- Explain GIL in Python.
- Explain threading vs multiprocessing vs asyncio in Python.
- Explain generators in Python.