[lenzm]

Yes, it gets a trailing comma if it's on it's own line. That way when you add/remove arguments in a multi-line call it's only a one-line diff. This doesn't apply when the diff is only one line anyway.

Who's to say you don't add a new argument to the function in the future, like

    my_print(
        "This string has two parameters, `a` which is equal to {a} and `b` which is equal to {b}",
        a=1,
        b=2,
        color_negative_red=True,
    )

[maratc]

> it gets a trailing comma if it's on it's own line.

Sorry but it doesn't make any sense to me. If your argument is "a trailing comma is a good thing," it should go into any and all function calls/list declarations/etc. Who's to say I won't add this in the future:

    my_print("a={a}, b={b}", a=1, b=2, color_negative_red=True)

So do I need to have this now?

    my_print("a={a}, b={b}", a=1, b=2,)

There's a very responsive playground at https://black.vercel.app/ and whatever it does looks strange to me, because the underlying assumptions look inconsistent one with the other (to my eye at least.) Specifically, "the length of the string should decide whether there is a trailing comma or there isn't" makes zero sense.

[thfuran]

>Sorry but it doesn't make any sense to me. If your argument is "a trailing comma is a good thing," it should go into any and all function calls/list declarations/et

No, the argument is quite specifically that a one line diff to add a new argument/element to the end of a list is preferable to a two line diff to do the same thing. The presence of the trailing comma is necessary to achieve that only when elements are on their own line.

[maratc]

Ok, we're then back to `print` example:

    print(
        'Hello there from a very long line abcdefghijklmnopqrstuvwxyz',
        sep=' ', 
        end='\n', 
        file=None, 
        flush=False,
    )

All of the existing named parameters to `print()` function are already provided, and that standard function is highly unlikely to change. Should I add another string to `print`, I will have to do it before the named parameters anyway. There is no sense in the trailing comma here however you look at it.

Edit: sorry for using single quotes, in my 20 years of writing Python it was never an issue, but now with `black` it apparently is.

[iainmerrick]

I think this boils it down to the essence. Whether you use a trailing comma here, and whether you use single or double quotes, is just bike-shedding. If there's an automated tool that can make a consistent choice everywhere, that's worthwhile.