Unused Method Parameter

ID

python.unused_method_parameter

Severity

low

Remediation Complexity

trivial

Remediation Risk

low

Remediation Effort

low

Resource

Dead Code

Language

Python

Tags

dead-code, reliability

Description

Reports a function or method parameter that is never read in the body. Unused parameters are usually leftovers from a refactor or scaffolding from an interface-driven contract that has since changed.

def f(a, b):                  # FLAW on b — never read
    return a

def g(a, _ignored):           # OK — leading underscore is intentional
    return a

self / cls are excluded (Python’s calling convention requires them). Dunder methods (init, eq, etc.) are excluded — their signature is fixed by the protocol. Decorated functions are excluded — decorators commonly mandate the signature. Methods on classes whose body reads no parameter at all are excluded — that’s almost always an interface stub or override.

Rationale

An unused parameter is a hint to the reader that something is wrong with the function’s contract: either the parameter was meant to be used and isn’t, or it was kept for backward compatibility and should be removed if no caller relies on it.

Remediation

  • Delete the parameter from the signature and call sites.

  • Rename to _name to signal "intentional, do not use".

  • Restore the missing read if the typo dropped it.

References