Add additional attributes to re.error

[serhiy-storchaka]

BPO	22578
Nosy	@pitrou, @ezio-melotti, @serhiy-storchaka
Files	re_error_attrs.patch re_error_attrs2.patch re_error_attrs3.patch re_error_attrs4.patch

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = 'https://github.com/serhiy-storchaka'
closed_at = <Date 2014-11-10.12:43:24.800>
created_at = <Date 2014-10-08.12:45:10.228>
labels = ['expert-regex', 'type-feature']
title = 'Add additional attributes to re.error'
updated_at = <Date 2014-12-01.09:27:20.102>
user = 'https://github.com/serhiy-storchaka'

bugs.python.org fields:

activity = <Date 2014-12-01.09:27:20.102>
actor = 'python-dev'
assignee = 'serhiy.storchaka'
closed = True
closed_date = <Date 2014-11-10.12:43:24.800>
closer = 'serhiy.storchaka'
components = ['Regular Expressions']
creation = <Date 2014-10-08.12:45:10.228>
creator = 'serhiy.storchaka'
dependencies = []
files = ['36834', '36836', '36852', '36860']
hgrepos = []
issue_num = 22578
keywords = ['patch']
message_count = 11.0
messages = ['228787', '228788', '228793', '228820', '228874', '228972', '230953', '230956', '230959', '230960', '231920']
nosy_count = 5.0
nosy_names = ['pitrou', 'ezio.melotti', 'mrabarnett', 'python-dev', 'serhiy.storchaka']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue22578'
versions = ['Python 3.5']

[serhiy-storchaka]

Proposed patch adds additional attributes to the re.error exception: msg, pattern, pos, colno, lineno. It also adds helpful information to error message.

Examples:

>>> re.compile(r"abc\u123")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/serhiy/py/cpython/Lib/re.py", line 220, in compile
    return _compile(pattern, flags)
  File "/home/serhiy/py/cpython/Lib/re.py", line 287, in _compile
    p = sre_compile.compile(pattern, flags)
  File "/home/serhiy/py/cpython/Lib/sre_compile.py", line 465, in compile
    p = sre_parse.parse(p, flags)
  File "/home/serhiy/py/cpython/Lib/sre_parse.py", line 797, in parse
    p = _parse_sub(source, pattern, 0)
  File "/home/serhiy/py/cpython/Lib/sre_parse.py", line 387, in _parse_sub
    itemsappend(_parse(source, state))
  File "/home/serhiy/py/cpython/Lib/sre_parse.py", line 767, in _parse
    code = _escape(source, this, state)
  File "/home/serhiy/py/cpython/Lib/sre_parse.py", line 378, in _escape
    raise source.error("bogus escape: %s" % repr(escape), len(escape))
sre_constants.error: bogus escape: '\\u123' at position 3
>>> re.compile("""
...     (?x)
...     .++
... """)
Traceback (most recent call last):
  File "<stdin>", line 4, in <module>
  File "/home/serhiy/py/cpython/Lib/re.py", line 220, in compile
    return _compile(pattern, flags)
  File "/home/serhiy/py/cpython/Lib/re.py", line 287, in _compile
    p = sre_compile.compile(pattern, flags)
  File "/home/serhiy/py/cpython/Lib/sre_compile.py", line 465, in compile
    p = sre_parse.parse(p, flags)
  File "/home/serhiy/py/cpython/Lib/sre_parse.py", line 797, in parse
    p = _parse_sub(source, pattern, 0)
  File "/home/serhiy/py/cpython/Lib/sre_parse.py", line 387, in _parse_sub
    itemsappend(_parse(source, state))
  File "/home/serhiy/py/cpython/Lib/sre_parse.py", line 602, in _parse
    source.tell() - here + len(this))
sre_constants.error: multiple repeat at position 16 (line 3, column 7)

See also PEP-473, bpo-19361 and bpo-22364.

[pitrou]

Sounds ok, but it would be nice to add some tests.

[serhiy-storchaka]

Sounds ok, but it would be nice to add some tests.

Thank you. Here is a patch with added test.

[mrabarnett]

I prefer to include the line and column numbers if it's a multi-line pattern, not just if the line number is > 1.

BTW, it's shorter if you do this:

    self.colno = pos - pattern.rfind(newline, 0, pos)

If there's no newline, .rfind will return -1.

[serhiy-storchaka]

Thank you Matthew for your suggestions. Here is updated patch.

[serhiy-storchaka]

Synchronized with the tip after bpo-19380 changes.

[ezio-melotti]

LGTM.

[python-dev]

New changeset 292c4d853662 by Serhiy Storchaka in branch 'default':
Issue bpo-22578: Added attributes to the re.error class.
https://hg.python.org/cpython/rev/292c4d853662

[python-dev]

New changeset 07f082b200a7 by Serhiy Storchaka in branch 'default':
Fixed IDLE tests after changing re error messages (issue bpo-22578).
https://hg.python.org/cpython/rev/07f082b200a7

[serhiy-storchaka]

Thank you Ezio for your review.