Feature or enhancement

Proposal:

It would be nice if the following worked as expected:

m=re.match(r"(a)(b)(c)","abc")assertisinstance(m,Sequence)assertlen(m)==4assertlist(m)== ["abc","a","b","c"]abc,a,b,c=massertabc=="abc"anda=="a"andb=="b"andc=="c"matchre.match(r"(\d+)-(\d+)-(\d+)","2025-05-07"):case [_,year,month,day]:assertyear=="2025"andmonth=="05"andday=="07"

If you also work with Javascript this will feel very familiar:

letm="abc".match(/(a)(b)(c)/)console.log(minstanceofArray)// trueconsole.log(m.length)// 4console.log(Array.from(m))// [ 'abc', 'a', 'b', 'c' ]let[abc,a,b,c]=mconsole.log(abc)// abcconsole.log(a)// aconsole.log(b)// bconsole.log(c)// c

Back in 2016, there.Match object API was expanded to include__getitem__ as a shortcut for.group(...).

The goal was to improve usability and approachability by makingre.Match objects fit a bit more seamlessly into python's core data model. Accessing groups via subscripting is now intuitive, but becausere.Match objects only have a__getitem__ and no__len__, they can't be used as a properSequence type.

To me, this always felt a bit awkward. After digging up theoriginal discussion, it seems like the reason why__len__ didn't make it was that it was still undecided whether the returned value should take into account group0 or not.

Almost a decade later, as a user, the way I see it is that the__getitem__ implementation we're now used to suggests a regularSequence type that also happens to transparently translate group names provided as subscript to their corresponding group index. In fact, this is actually how it works in the underlying C code.

With this in mind, we can simply define__len__ taking into account group0, and we'll finally be able to enjoy coherentre.Match objects that behave as properSequence types.

Has this already been discussed elsewhere?

https://discuss.python.org/t/make-re-match-a-well-rounded-sequence-type/91039

Links to previous discussion of this feature:

Improve the usability of the match object named group API (605bdae)

Linked PRs

• gh-133546: Makere.Match a well-roundedSequence type #133549