[Python-ideas] 1_000_000

[Steven D'Aprano]

Bruce Leban wrote:

> Consider these examples instead:
> 
>    - 1_234_000
>    - 9.876_543_210
>    - 0xFEFF_0042
> 
> I'm not advocating this change (nor against it); I just think the discussion
> should be focused on the actual idea. I do have a question:
> 
> Is _ just ignored in numbers or are there more complex rules?
> 
>    - 1_2345_6789  (can I use groups of other sizes instead?)
>    - 1_2_3_4_5  (ditto)
>    - 1_234_6789  (do all the groups need to be the same size?)

+1 on all of these. I don't particularly like the look of _ as a number 
separator, but it's hard to think of any alternatives other than space, 
and some separator is better than long sequences of digits.

I'm -0.5 on spaces even though it looks MUCH better, because it's too 
easy to leave the commas out in lists etc:

L = [1, 2, 3, 4 5, 6, 7, 8, 9, 10]  # oops, wanted 4 & 5 not 45

(Admittedly if the items where strings, the same failure mode applies.)


>    - 1_   (must the _ only be in between 2 digits?)
>    - 1__234   (what about multiple _s?)

-1 on allowing either _1 or 1_ as numbers.

-0 on allowing doubled underscores.


>    - 9.876_543_210   (can it be used to the right of the decimal point?)
>    - 0xFEFF_0042   (can it be used in hex, octal or binary numbers?)

+1 on these two.


>    - int('123_456')   (do other functions accept this syntax too?)

That's a tricky one... I'd say No, but I'm not entirely sure. It's easy 
enough to say:

int('123_456'.replace('_', ''))

albeit a tad verbose. Also easy to say:

int('123' '456')

which is less verbose. And it will change the behaviour of the int 
function. So I don't think we need to support separators inside strings.

We can always change our mind later and add it in, but it's much harder 
to take it out later.



-- 
Steven