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Sarj Sarj Sarj Standards

prefer-struct-over-namedtuple

Prefer typed declarations for static application-owned collections.namedtuple records.

SARJ015 Rule source Tests Catalog JSON

Why

A static collections.namedtuple factory declares field names but cannot declare their types.

Fix

Use a class-based typing.NamedTuple when tuple behavior is part of the contract. Use a frozen, slotted dataclass or an existing validation model only when changing tuple semantics is safe.

Examples

Before — flagged Static record omits field types
models.py
from collections import namedtuple


Row = namedtuple("Row", ["id", "name"])
After — preferred Typed tuple-compatible record
models.py
from typing import NamedTuple




class Row(NamedTuple):
    id: int
    name: str




row = Row(1, "Ada")
id, name = row