[Python-ideas] Fwd: Fwd: unpacking generalisations for list comprehension

[Chris Angelico]

On Sun, Oct 16, 2016 at 4:38 AM, אלעזר <elazarg at gmail.com> wrote:
> On Sat, Oct 15, 2016 at 8:36 PM Chris Angelico <rosuav at gmail.com> wrote:
>>
>> On Sun, Oct 16, 2016 at 4:33 AM, אלעזר <elazarg at gmail.com> wrote:
>> > You are confusing here two distinct roles of the parenthesis:
>> > disambiguation
>> > as in "(1 + 2) * 2", and tuple construction as in (1, 2, 3). This
>> > overload
>> > is the reason that (1) is not a 1-tuple and we must write (1,).
>>
>> Parentheses do not a tuple make. Commas do.
>>
>> 1, 2, 3, # three-element tuple
>> 1, 2, # two-element tuple
>> 1, # one-element tuple
>>
> And what [1, 2, 3] means? It's very different from [(1,2,3)].
>
> Python explicitly allow 1, 2, 3 to mean tuple in certain contexts, I agree.
>

Square brackets create a list. I'm not sure what you're not understanding, here.

The comma does have other meanings in other contexts (list/dict/set
display, function parameters), but outside of those, it means "create
tuple".

ChrisA