Formatter: Option for compact wrapping comma-separated constructs

[danransdorf]

Proposal

Hello, would you consider an option to keep multiple items on the same line when they fit?

For example, Ruff currently formats this as:

foo(
    a=a,
    b=b,
    c=c,
    d=d,
)

list1 = [
    foo1,
    foo2,
    foo3,
    foo4,
]

I’d prefer something like:

foo(
    a=a, b=b, c=c,
    d=d,
)

list1 = [
    foo1, foo2,
    foo3, foo4,
]

Basically packing items onto a continuation line until it hits the configured line-length. Similar behavior exists in clang-format as parameter “bin packing”, and similar style is common in F#. YAPF can do this as well, and it’s the main thing keeping me from fully switching to Ruff.

I’m not suggesting changing Ruff’s default formatting here, I’d be happy for this to be an opt-in formatter option.
I know Ruff intentionally keeps formatter options limited, so I’m mostly wondering if this is something you’d consider at all. Otherwise I may just keep a small fork.

I’d be happy to try implementing this option, if it fits Ruff’s direction.

Similar discussions

The closest discussions I found mostly touch on related skip-magic-trailing-comma option.

• Option to vertically format arguments if wrapped. #9992
• Formatter: Beta feedback #7310

Examples (for more illustration)

Calls with several kwargs

This becomes noticeable with calls that have bunch of short kwargs:

await publish_event(
    user_id=user_id,
    request_id=request_id,
    event_type="UPLOAD_COMPLETED",
    source="api",
    retry_count=retry_count,
    attempt=attempt,
    region=region,
    bucket=bucket,
    file_name=file_name,
    metadata={"size": size, "format": file_format},
)

await publish_event(
    user_id=user_id,
    request_id=request_id,
    event_type="UPLOAD_FAILED",
    source="api",
    retry_count=retry_count,
    attempt=attempt,
    region=region,
    bucket=bucket,
    file_name=file_name,
    metadata={"reason": reason, "status": status},
)

I'd prefer:

await publish_event(
    user_id=user_id, request_id=request_id, event_type="UPLOAD_COMPLETED",
    source="api", retry_count=retry_count, attempt=attempt, region=region,
    bucket=bucket, file_name=file_name,
    metadata={"size": size, "format": file_format},
)

await publish_event(
    user_id=user_id, request_id=request_id, event_type="UPLOAD_FAILED",
    source="api", retry_count=retry_count, attempt=attempt, region=region,
    bucket=bucket, file_name=file_name,
    metadata={"reason": reason, "status": status},
)

Database calls / tuples

Same thing with database calls with tuples:

cursor.execute(
    """
    INSERT INTO users (
        id, email, username, created_at, updated_at,
        status, role, organization_id, last_login_at, is_active
    ) VALUES (
        ?, ?, ?, ?, ?, ?, ?, ?, ?, ?
    )
    """,
    (
        user.id,
        user.email,
        user.username,
        user.created_at,
        user.updated_at,
        user.status,
        user.role,
        user.organization_id,
        user.last_login_at,
        user.is_active,
    ),
)

I'd prefer:

cursor.execute(
    """
    INSERT INTO users (
        id, email, username, created_at, updated_at,
        status, role, organization_id, last_login_at, is_active
    ) VALUES (
        ?, ?, ?, ?, ?, ?, ?, ?, ?, ?
    )
    """,
    (
        user.id, user.email, user.username, user.created_at,
        user.updated_at, user.status, user.role, user.organization_id,
        user.last_login_at, user.is_active,
    ),
)

[MichaReiser]

Some previous discussions

• Lists: Formatter: Support putting multiple items per line for large sequences #11886
• Proposal: Formatting options to enable "vertical formatting" and "grid formatting" #8197