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 "<stdin>", line 1, in <module>
  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

The last line "re.error: nothing to repeat at position 0" shows that you should not put raw * as the first element, use \* instead.

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 <report@bugs.python.org> wrote:

>
> Windson Yang <wiwindson@gmail.com> 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 <report@bugs.python.org>
> <https://bugs.python.org/issue35146>
> _______________________________________
>

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.

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 <report@bugs.python.org> wrote:

>
> Steven D'Aprano <steve+python@pearwood.info> 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 <report@bugs.python.org>
> <https://bugs.python.org/issue35146>
> _______________________________________
>