New submission from Serhiy Storchaka <storchaka+cpyt...@gmail.com>: Currently `{m}`, `{m,n}`, `{m,}` and `{,n}` where m and n are non-negative decimal numbers are accepted in regular expressions as quantifiers that mean repeating the previous RE from m (0 by default) to n (infinity by default) times.
But if the opening brace '{'is not followed by one of the above patterns, it means just the literal '{'. >>> import re >>> re.search('(foobar){e}', 'xirefoabralfobarxie') >>> re.search('(foobar){e}', 'foobar{e}') <re.Match object; span=(0, 9), match='foobar{e}'> This conflicts with the regex module which uses braces for defining the "fuzzy" matching. >>> import regex >>> regex.search('(foobar){e}', 'xirefoabralfobarxie') <regex.Match object; span=(0, 6), match='xirefo', fuzzy_counts=(6, 0, 0)> >>> regex.search('(foobar){e}', 'foobar{e}') <regex.Match object; span=(0, 6), match='foobar'> I don't think it is worth to add support of fuzzy matching in the re module, but for compatibility it would be better to raise an error or a warning in case of '{' not following by the one of the recognized patterns. This could also help to catch typos and errors in regular expressions, i.e. in '-{1.2}' or '-{1, 2}' instead of '-{1,2}'. Possible variants: 1. Emit a DeprecationWarning in 3.7 (and 2.7.15 with the -3 option), raise a re.error in 3.8 or 3.9. 2. Emit a PendingDeprecationWarning in 3.7, a DeprecationWarning in 3.8, and raise a re.error in 3.9 or 3.10. 3. Emit a RuntimeWarning or SyntaxWarning in 3.7 and forever. 4. Emit a FutureWarning in 3.7, and implement the fuzzy matching or replace re with regex sometimes in future. Unlikely. ---------- assignee: serhiy.storchaka components: Library (Lib), Regular Expressions messages: 306479 nosy: ezio.melotti, mrabarnett, serhiy.storchaka priority: normal severity: normal status: open title: Deprecate accepting type: enhancement versions: Python 3.7 _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue32067> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com