re invalid escape sequence isn't: \( and \)

[ethanfurman]

Bug report

Bug description:

According to the docs:

(...)
Matches whatever regular expression is inside the parentheses, and indicates the start and end of a group; the contents of a group can be retrieved after a match has been performed, and can be matched later in the string with the \number special sequence, described below. To match the literals '(' or ')', use \( or \), or enclose them inside a character class: [(], [)].

However, when I try to use the \( and \) literals, I get:

SyntaxWarning: invalid escape sequence '\('
  return bool(re.match('^Custom\([^)]*\)$', text))

Note that using the character classes [(] and [)] does work, but in my opinion re strings are hard enough to read as-is. ;-)

Tested on 3.12 and 3.13.

CPython versions tested on:

3.13

Operating systems tested on:

Linux

[StanFromIreland]

I think this is just from Python parsing the string. Try with a raw string.

[ethanfurman]

Wow. I wish I would stop forgetting to use raw strings with re!

Thanks!

[tim-one]

This has nothing to do with regexps: it's an invalid escape sequence for plain old Python strings:

>>> '\('
<python-input-8>:1: SyntaxWarning: invalid escape sequence '\('

[StanFromIreland]

Wow. I wish I would stop forgetting to use raw strings with re!

Just remember, r for regex :-)