QUAL019warningPro

duplicate-code-blocks

Near-identical function/component exists in another file — extract to shared module.

Applies to: Project-level

Why this matters

When the same large function or component is copy-pasted across files, changes to one copy don't update the other. Over time the copies drift apart, leading to subtle inconsistencies and doubled maintenance effort. Extract the shared logic into a common module and import from there.

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 24 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