Constructors in Python — Python Technical Interview Questions & Answers

Constructors in Python

Constructors in Python

  • __init__ is the initializer most people mean by constructor. It runs when you create the object: s = Student("Asha", 12). Inside, self.name = name stores fields. You do not call __init__ yourself. Student(...) does it. Forget self on the first parameter and you get TypeError.
  • __new__ actually creates the instance — advanced, skip unless they ask. Viva signature: def __init__(self, name, roll). Then one object on the board: print(s.name) → Asha.
  • Constructors in Python — output: 4. Box(4) calls __init__ and sets side.

Technical Interview Tip: __init__(self, ...) + one Student example.

Code Examples for Constructors in Python

Example

# Constructor
class Box:
    def __init__(self, side):
        self.side = side

b = Box(4)
print(b.side)

Constructors in Python — output: 4. Box(4) calls __init__ and sets side.

How to Explain Constructors in Python to an Interviewer

Explain Constructors as if you are teaching a junior — definition, then one tiny script.

__init__ runs on create. self first. Store attributes.

What does the example print, and why?

Constructors in Python — output: 4

What mistake do freshers make with Constructors?

Don’t call __init__ by hand.