[New-bugs-announce] [issue40394] difflib.SequenceMatcher.find_longest_match default arguments

[Lewis Ball]

New submission from Lewis Ball <lrjball at gmail.com>:

The usage of difflib.SequenceMatcher.find_longest_match could be simplified for the most common use case (finding the longest match between the entirety of the two strings) by taking default args.

At the moment you have to do:

>>> from difflib import SequenceMatcher
>>> a, b = 'foo bar', 'foo baz'
>>> s = SequenceMatcher(a=a, b=b)
>>> s.find_longest_match(0, len(a), 0, len(b))
Match(a=0, b=0, size=6)

but with default args the final line could be simplified to just:

>>> s.find_longest_match()
Match(a=0, b=0, size=6)

which seems to be much cleaned and more readable.


I'd suggest updating the code so that the function signature becomes:

find_longest_match(alo=None, ahi=None, blo=None, bhi=None)

which is consistent with the current docstring of "Find longest matching block in a[alo:ahi] and b[blo:bhi]." as `a[None:None]` is the whole of `a`.

I think this would only be a minor code change, and if it is something that would be useful I'd be happy to have a go at a PR.

----------
components: Library (Lib)
messages: 367306
nosy: Lewis Ball
priority: normal
severity: normal
status: open
title: difflib.SequenceMatcher.find_longest_match default arguments
type: enhancement

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue40394>
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