Dataclass features in Python

Beyond the basics: ordering, defaults, and frozen data.

from dataclasses import dataclass, field


@dataclass(order=True)
class Task:
    priority: int
    title: str = "untitled"
    tags: list[str] = field(default_factory=list)


@dataclass(frozen=True)
class Config:
    host: str
    port: int = 8080


urgent = Task(1, "ship it", tags=["release"])
later = Task(5)
ordered = sorted([later, urgent])

How it works

1. @dataclass(order=True) derives comparison methods.
2. field(default_factory=list) avoids shared mutable defaults.
3. frozen=True makes instances immutable.

Keywords and builtins used here

• Config
• Task
• class
• int
• list
• sorted
• str

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Step 2 of 4 in Typing & dataclasses, step 21 of 53 in Pythonic Python.

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