[New-bugs-announce] [issue39165] Completeness and symmetry in RE, avoid `findall(...)[0]`

[Juancarlo Añez]

New submission from Juancarlo Añez <apalala at gmail.com>:

The problematic `findall(...)[0]` is a common anti-pattern in Python programs. The reason is lack of symmetry and completeness in the `re` module.

The original proposal in `python-ideas` was to add `re.findfirst(pattern, string, flags=0, default=_mark)` with more or less the semantics of `next(findall(pattern, string, flags=flags), default=default)`. 

The referenced PR adds `findalliter(pattern, string, flags=0)` with the value semantics of `findall()` over a generator, implements `findall()` as `return list(findalliter(...))`, and implements `findfirst()`. 

Consistency and correctness are likely because all tests pass with the redefined `findall()`.

----------
components: Library (Lib)
messages: 359039
nosy: apalala
priority: normal
pull_requests: 17191
severity: normal
status: open
title: Completeness and symmetry in RE, avoid `findall(...)[0]`
type: enhancement
versions: Python 3.8

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue39165>
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