pydantic_slots_usage.py

# /// script
# dependencies = [
#   "pydantic",
# ]
# ///


from pydantic import BaseModel


class User(BaseModel):
    id: int
    name: str


# Confirm slots are present
print("__slots__" in dir(User))  # True
print(hasattr(User, "__slots__"))  # True
print(User.__slots__)  # ('__fields_set__', '__dict__', '__pydantic_private__', etc.)

# Confirm dynamic attributes are blocked (unlike regular classes)
u = User(id=1, name="Bob")
try:
    u.foo = "bar"
except AttributeError as e:
    print("No dynamic attributes allowed:", e)