Lambda returning tuple question, multi-expression

Cameron Simpson cs at cskk.id.au
Fri Mar 10 16:08:21 EST 2023


On 09Mar2023 17:55, aapost <aapost at idontexist.club> wrote:
>On 3/9/23 16:37, Cameron Simpson wrote:
>>Just a note that some code formatters use a trailing comma on the last 
>>element to make the commas fold points. Both yapf (my preference) and 
>>black let you write a line like (and, indeed, flatten if short 
>>enough):
>>
>>     ( a, b, c )
>>
>>but if you write:
>>
>>     ( a, b, c, )
>>
>>they'll fold the lines like:
>>
>>     ( a,
>>       b,
>>       c,
>>     )
>>Cameron Simpson <cs at cskk.id.au>
>
>
>Thanks for the info, good to know, I actually do like the idea of 
>trailing commas for tuples (helps prevent things like the difference 
>between ("abc") and ("abc",) and makes swapping things around nicer.

Just keep in mind that if you restructure code with copy/paste it can be 
a small issue (not really tied to the trailing comma but commas in 
general. More than once I've been bitten by doing roughly this:

     f( a,
        b=x+y,
     )

shuffled to:

     b=x+y,
     f( a,
        b=b,
     )

Whoops! It shows up almost immediately, but the first time it took me a 
while to see that stray comma.

>I've just been using a lot of json lately and it has been 
>subconsciously training me different, lol.

Yes, it hates the trailing comma. So annoying.

Cheers,
Cameron Simpson <cs at cskk.id.au>


More information about the Python-list mailing list