Python · maintainability

prefer-or-pattern

python:prefer-or-pattern

Merge adjacent `case` arms with identical bodies into one or-pattern.

Code: SARJ070
Default: error
Fix: none
Languages: python

Why

An or-pattern expresses shared handling once and prevents identical arms from drifting apart.

Fix

Join the equivalent patterns with `|` and keep their shared body under the merged arm.

Before / after

Executed by this rule’s unit tests.

Before

Adjacent match arms repeat one body

app/settings.py · focus

def configure(value):
    match value:
        case LocalSettings():
            return build(value)
        case RemoteSettings():
            return build(value)

After

One or-pattern owns the shared body

app/settings.py · focus

def configure(value):
    match value:
        case LocalSettings() | RemoteSettings():
            return build(value)

Limits

Only adjacent, unguarded, refutable arms with structurally identical non-empty bodies are compared.
Arms with different bound names or comments are excluded because merging can change meaning or intent.