On Wed, Dec 4, 2019 at 3:02 PM Guido van Rossum <gu...@python.org> wrote:
> Fair enough. I’ll let the OP defend his use case.
>
The OP thinks that the case for wanting just the string for a first regex
match, or a verifiable default if there is no match, is way too common,
that the advice on the web is not very good (it should be "write a
findfirst() using next() over finditer()", and that novices default to
using findall(..)[0], which is troublesome.
The proposed implementation of a findfirst() would handle many common
cases, and be friendly to newcomers (why do I need to deal with a Match
object?), specially if the semantics are those of *findall()*:
next(iter(findall(...)), default=default)
BTW, a common function in extensions to *itertools* is *first():*
def first(seq, default=None):
return next(iter(seq), default= default)
That function, *first()*, would also be a nice addition in *itertools*, and
*findfirst()* could be implemented using it. *first()* avoids most use
cases needing to check if a sequence or iterator is empty before using a
default value. MHO is that *first()* deals with so many common cases that
it should be a builtin.
Note that the case for *findfirst()* is weaker if *first()* is available.
Yet *findfirst()* solves the bigger problem.
--
Juancarlo *Añez*
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