QUAL019warningPro

duplicate-code-blocks

Duplicated code (whole function or repeated block, in this file or another) — extract it into a shared helper.

Applies to: Project-level

Why this matters

When the same logic is copied — a whole component pasted between pages, or a ten-line validation block repeated in every handler — changes to one copy don't reach the others. The copies drift, bugs get fixed in one place and not the rest, and every future change costs N times as much. Renaming the variables doesn't make it a different function. Extract the shared logic into one helper and call it from each site.

Catch it before it ships

pip install stablestack # or: npx stablestackstablestack # scans your project, QUAL019 includedstablestack explain QUAL019

QUAL019 is part of the Pro rule set. See pricing — the free tier ships 25 checks with no signup.

False positive in your codebase? Suppress a single line with # noqa: QUAL019

More Code Quality checks

exception-swallowing

Silently swallowed exceptions hide bugs and make debugging hard

unnamed-thread

Threads without names are hard to identify in debugging tools

complex-tuple

Tuples with 3+ elements are hard to understand - use a dataclass instead

mutable-default-argument

Mutable default arguments are shared between calls and cause bugs

print-statement

Print statements are typically debugging code that shouldn't be committed

todo-comment

TODO/FIXME comments indicate incomplete or problematic code

broad-exception

Catching all exceptions hides bugs and makes debugging hard

magic-number

Magic numbers make code hard to understand and maintain