Dataclasses and attrs

from dataclasses import dataclass, field

@dataclass
class Person:
    name: str
    age: int
    email: str = ""

# Automatic __init__, __repr__, __eq__
p = Person("Alice", 30)
print(p)  # Person(name='Alice', age=30, email='')

from dataclasses import dataclass, field
from typing import List

@dataclass
class Product:
    name: str
    price: float
    tags: List[str] = field(default_factory=list)
    _id: int = field(init=False, repr=False)

    def __post_init__(self):
        self._id = hash(self.name)

# Frozen (immutable)
@dataclass(frozen=True)
class Point:
    x: float
    y: float

# Ordered comparison
@dataclass(order=True)
class Student:
    sort_index: float = field(init=False, repr=False)
    name: str
    grade: float

    def __post_init__(self):
        self.sort_index = self.grade

@dataclass
class Animal:
    name: str
    age: int

@dataclass
class Dog(Animal):
    breed: str

dog = Dog("Buddy", 5, "Labrador")

from dataclasses import asdict, astuple

@dataclass
class Person:
    name: str
    age: int

p = Person("Alice", 30)
print(asdict(p))   # {'name': 'Alice', 'age': 30}
print(astuple(p))  # ('Alice', 30)

@dataclass(slots=True)  # Python 3.10+
class Point:
    x: float
    y: float
# Uses __slots__ for memory efficiency