[issue13899] re pattern r"[\A]" should work like "A" but matches nothing. Ditto B and Z.

Ezio Melotti added the comment: Fixed, thanks for the report John, and for the patch Matthew! -- resolution: -> fixed stage: patch review -> committed/rejected status: open -> closed ___ Python tracker ___

[issue13899] re pattern r"[\A]" should work like "A" but matches nothing. Ditto B and Z.

Roundup Robot added the comment: New changeset 2bc04449fd8c by Ezio Melotti in branch '2.7': #13899: \A, \Z, and \B now correctly match the A, Z, and B literals when used inside character classes (e.g. [A]). Patch by Matthew Barnett. http://hg.python.org/cpython/rev/2bc04449fd8c New changeset

[issue13899] re pattern r"[\A]" should work like "A" but matches nothing. Ditto B and Z.

Changes by Ezio Melotti : -- assignee: -> ezio.melotti stage: needs patch -> patch review ___ Python tracker ___ ___ Python-bugs-list

[issue13899] re pattern r"[\A]" should work like "A" but matches nothing. Ditto B and Z.

Matthew Barnett added the comment: I've attached a patch. -- keywords: +patch Added file: http://bugs.python.org/file28614/issue13899.patch ___ Python tracker ___ ___

[issue13899] re pattern r"[\A]" should work like "A" but matches nothing. Ditto B and Z.

Changes by Ezio Melotti : -- stage: -> needs patch versions: +Python 3.3, Python 3.4 ___ Python tracker ___ ___ Python-bugs-list mail

[issue13899] re pattern r"[\A]" should work like "A" but matches nothing. Ditto B and Z.

Matthew Barnett added the comment: In re, "\A" within a character set should be similar to "\C", but instead it's still interpreted as meaning the start of the string. That's definitely a bug. If it doesn't do what it's supposed to do, then it's a bug. regex tries to be backwards compatible w

[issue13899] re pattern r"[\A]" should work like "A" but matches nothing. Ditto B and Z.

Terry J. Reedy added the comment: I presume you intend regex to match the spec rather than bugs. So if re has a bug in an obsure corner case and the spec is ambiguous, as I have the impression is the case here, using the interpretation embodied in regex would avoid creating a conflict. -

[issue13899] re pattern r"[\A]" should work like "A" but matches nothing. Ditto B and Z.

Matthew Barnett added the comment: This should answer that question: >>> re.findall(r"[\A\C]", r"\AC") ['C'] >>> regex.findall(r"[\A\C]", r"\AC") ['A', 'C'] The behaviour of regex is intended to match that of re for backwards compatibility. -- ___

[issue13899] re pattern r"[\A]" should work like "A" but matches nothing. Ditto B and Z.

Terry J. Reedy added the comment: Does anyone have regex installed, to see what it does? -- nosy: +terry.reedy ___ Python tracker ___ ___

[issue13899] re pattern r"[\A]" should work like "A" but matches nothing. Ditto B and Z.

Changes by Jesús Cea Avión : -- nosy: +jcea ___ Python tracker ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.

[issue13899] re pattern r"[\A]" should work like "A" but matches nothing. Ditto B and Z.

Ezio Melotti added the comment: The rule 1 makes sense, but it's not entirely obvious (people might consider bBaAzZ special too). The "normal Python rules for backslash escapes but revert to the C behaviour of stripping the \ from unrecognised escapes" is not obvious either, and from r'[\A]'

[issue13899] re pattern r"[\A]" should work like "A" but matches nothing. Ditto B and Z.

John Machin added the comment: Whoops: "normal Python rules for backslash escapes" should have had a note "but revert to the C behaviour of stripping the \ from unrecognised escapes" which is what re appears to do in its own \ handling. -- ___ Pyth

[issue13899] re pattern r"[\A]" should work like "A" but matches nothing. Ditto B and Z.

John Machin added the comment: @Ezio: Comparison of the behaviour of \letter inside/outside character classes is irrelevant. The rules for inside can be expressed simply as: 1. Letters dDsSwW are special; they represent categories as documented, and do in fact have a similar meaning outside c

[issue13899] re pattern r"[\A]" should work like "A" but matches nothing. Ditto B and Z.

Georg Brandl added the comment: Interesting. That shifts the issue, since the current behavior is neither of the two that make sense. Then it would indeed make the most sense to raise in these cases. (I wonder what these patterns actually would match, but I have no time to look in the sre so

[issue13899] re pattern r"[\A]" should work like "A" but matches nothing. Ditto B and Z.

Ezio Melotti added the comment: [\w] should definitely work, but [\B] doesn't seem to match anything useful, and it just fails silently because it's neither equivalent to \B nor to [B]: >>> re.match(r'foo\B', 'foobar') # on a non-word-boundary -- matches fine <_sre.SRE_Match object at 0xb76dd3

[issue13899] re pattern r"[\A]" should work like "A" but matches nothing. Ditto B and Z.

Georg Brandl added the comment: r'[\w]' also matches word chars. I find that a very useful property, since you can easily build classes like '[\w.]' It's also impossible to change this without breaking lots of regexes. It's also explicitly documented, although IMO it's not clear it extends

[issue13899] re pattern r"[\A]" should work like "A" but matches nothing. Ditto B and Z.

John Machin added the comment: @ezio: Of course the context is "inside a character class". I expect r'[\b]' to act like r'\b' aka r'\x08' aka backspace because (1) that is the treatment applied to all other C-like control char escapes (2) the docs say so explicitly: "Inside a character range,

[issue13899] re pattern r"[\A]" should work like "A" but matches nothing. Ditto B and Z.

Ezio Melotti added the comment: This happens because \A, \B and \Z are valid escape sequences[0]. If what you mean is that they shouldn't be recognized as such inside a character class, then I can agree with that. ^ and $ are similar to \A and \Z but they are considered as literals inside [].

[issue13899] re pattern r"[\A]" should work like "A" but matches nothing. Ditto B and Z.

New submission from John Machin : Expected behaviour illustrated using "C": >>> import re >>> re.findall(r'[\C]', 'CCC') ['C', 'C', 'C'] >>> re.compile(r'[\C]', 128) literal 67 <_sre.SRE_Pattern object at 0x01FC6E78> >>> re.compile(r'C', 128) literal 67 <_sre.SRE_Pattern object at 0x01FC6F08> I