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What does the @dataclass decorator automatically generate for a class? How do you create a simple immutable record using collections.namedtuple? How do you specify default values for dataclass fields, and what ordering restriction applies? Why can't you use a mutable default value (like an empty list) directly as a dataclass field default, and how do you use field(default_factory=...) to fix it? How does typing.NamedTuple differ from collections.namedtuple in terms of syntax and type annotation support? How do you add validation logic to a dataclass field using __post_init__? How do you use dataclasses.field(compare=False) or field(repr=False) to exclude a specific field from the auto-generated __eq__ or __repr__? How do you implement custom ordering (<, <=, >, >=) for a dataclass using order=True, and what constraint does it place on field comparison? How do you convert a dataclass instance to and from a dictionary using dataclasses.asdict() and manual reconstruction? How would you implement inheritance between dataclasses, and what field-ordering rule must be respected across the hierarchy?
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How do you make a dataclass immutable (read-only after creation) using frozen=True?

Intermediate

Answer

Pass frozen=True to the @dataclass decorator to make every field effectively read-only after __init__ runs — attempting to assign to any field afterward raises a FrozenInstanceError, and frozen dataclasses also automatically become hashable (if eq=True, the default), letting them be used as dict keys or set elements.
@dataclass(frozen=True)
class Point:
    x: int
    y: int

p = Point(1, 2)
# p.x = 99  # dataclasses.FrozenInstanceError: cannot assign to field 'x'

points_set = {Point(1, 2), Point(3, 4)}  # works: frozen dataclasses are hashable
Real-world example Creating an immutable value object (like a Point or Money amount) that's also safely usable as a dictionary key or set element.

Common follow-ups: Does frozen=True prevent mutation of a MUTABLE object stored INSIDE one of the dataclass's fields, like a list attribute?

Magic Methods & Operator Overloading
All 15 Dataclasses & NamedTuples questions