What is __slots__ optimization?

Question

Accepted Answer

**__slots__** — **memory and access time** savings.

```python
import sys

class Regular:
    def __init__(self, x, y):
        self.x = x
        self.y = y

class Optimized:
    __slots__ = ("x", "y")

def __init__(self, x, y):
        self.x = x
        self.y = y

# Object size
r = Regular(1, 2)
o = Optimized(1, 2)
print(f"Regular: {sys.getsizeof(r) + sys.getsizeof(r.__dict__)} bytes")
print(f"Optimized: {sys.getsizeof(o)} bytes")
# Regular: ~152 bytes
# Optimized: ~56 bytes

# Access speed
import timeit
print(timeit.timeit(lambda: r.x, number=1000000))  # Slower
print(timeit.timeit(lambda: o.x, number=1000000))  # Faster
```

**When to use:**
- Millions of objects.
- Memory-critical applications.
- High-performance requirements.

Python: What is slots optimization?