Python Data Classes and attrs: Clean Data Models Without Boilerplate

Python Data Classes

Python's dataclasses module generates boilerplate (init, repr, eq) automatically. They make clean, self-documenting data models without verbose manual class definitions.

from dataclasses import dataclass, field, asdict
from datetime import datetime

@dataclass
class User:
    id:         int
    name:       str
    email:      str
    role:       str       = 'member'
    tags:       list      = field(default_factory=list)
    created_at: datetime  = field(default_factory=datetime.now)

    def __post_init__(self):
        if '@' not in self.email:
            raise ValueError(f"Invalid email: {self.email}")
        self.name = self.name.strip().title()

u = User(id=1, name='rahul sharma', email='r@e.com')
print(u)           # User(id=1, name='Rahul Sharma', email='r@e.com', ...)
print(asdict(u))   # {'id': 1, 'name': 'Rahul Sharma', ...}

Frozen and Slots

@dataclass(frozen=True)   # immutable — hashable, usable as dict key
class Point:
    x: float
    y: float
    def distance(self): return (self.x**2 + self.y**2)**0.5

@dataclass(slots=True)    # Python 3.10+ — memory efficient
class Pixel:
    x: int
    y: int
    color: str = '#000000'