What is the difference between a constructor and an initializer?

Question

Accepted Answer

In Python, `__new__()` is the **constructor** (creates object). `__init__()` is the **initializer** (initializes object).

```python
class User:
    def __new__(cls, name):
        print("Creating object")
        return super().__new__(cls)

def __init__(self, name):
        print("Initializing object")
        self.name = name

u = User("Alice")
# Creating object
# Initializing object
```

**`__new__()`** is rarely overridden. Used for:
- Immutable types (`int`, `str`, `tuple`).
- Singleton pattern.
- Metaclasses.

**`__init__()`** — most initialization happens here.

Python: What is the difference between a constructor and an initializer?