[issue35146] Bad Regular Expression Broke re.findall()
New submission from Dan Boxall : Hi, I'm new to regular expressions and while playing around with them I tried this: >>> rex = '*New Revision:.* ([0-9]+)' >>> re.findall(rex, text) and got this: Traceback (most recent call last): File "", line 1, in File "C:\Python\Python37\lib\re.py", line 223, in findall return _compile(pattern, flags).findall(string) File "C:\Python\Python37\lib\re.py", line 286, in _compile p = sre_compile.compile(pattern, flags) File "C:\Python\Python37\lib\sre_compile.py", line 764, in compile p = sre_parse.parse(p, flags) File "C:\Python\Python37\lib\sre_parse.py", line 930, in parse p = _parse_sub(source, pattern, flags & SRE_FLAG_VERBOSE, 0) File "C:\Python\Python37\lib\sre_parse.py", line 426, in _parse_sub not nested and not items)) File "C:\Python\Python37\lib\sre_parse.py", line 651, in _parse source.tell() - here + len(this)) re.error: nothing to repeat at position 0 -- components: Regular Expressions messages: 329130 nosy: Callipygean, ezio.melotti, mrabarnett priority: normal severity: normal status: open title: Bad Regular Expression Broke re.findall() versions: Python 3.7 ___ Python tracker <https://bugs.python.org/issue35146> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue35146] Bad Regular Expression Broke re.findall()
Dan Boxall added the comment: Thank you. I realised that and if I put a dot in front it worked fine. But it should not break the function, so they will surely want to fix the bug? Kind regards, Dan Boxall On Fri, 2 Nov 2018 at 13:56, Windson Yang wrote: > > Windson Yang added the comment: > > The last line "re.error: nothing to repeat at position 0" shows that you > should not put raw * as the first element, use \* instead. > > -- > nosy: +Windson Yang > > ___ > Python tracker > <https://bugs.python.org/issue35146> > ___ > -- ___ Python tracker <https://bugs.python.org/issue35146> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue35146] Bad Regular Expression Broke re.findall()
Dan Boxall added the comment: Yes I realised that, as I said earlier. But it could say, "Invalid regular expression" and not produce ten lines of error messages. On Fri, 2 Nov 2018 at 14:21, Steven D'Aprano wrote: > > Steven D'Aprano added the comment: > > This is not a bug in Python, it is an invalid (broken) regular expression. > There is nothing that the interpreter or the regular expression engine can > do, because you are telling it to do something that makes no sense. What do > you expect findall to find, if you ask it to find something nonsensical? > > You say: > > "repeat this pattern any number of times" > > but there is no "this pattern" to be repeated. You are asking for > something impossible. The only legitimate response is to report back that > the regular expression is invalid and cannot be compiled, and fail > immediately. > > -- > nosy: +steven.daprano > resolution: -> not a bug > stage: -> resolved > status: open -> closed > > ___ > Python tracker > <https://bugs.python.org/issue35146> > ___ > -- ___ Python tracker <https://bugs.python.org/issue35146> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
