On Mon, Mar 16, 2020 at 02:36:25PM +0900, Stephen J. Turnbull wrote:
Kyle Stanley writes:
The behavior is the same on Python 3.8.2:
Python 3.8.2 (default, Feb 26 2020, 22:21:03) [GCC 9.2.1 20200130] on linux Type "help", "copyright", "credits" or "license" for more information.
r'x\'y' "x\\'y"
This looks like a defect to me. The "'" *is* being quoted.
If it's a defect, it's one which goes all the way back to Python 1.5: [steve@ando ~]$ python1.5 >>> r'x\'y' "x\\'y" and is fully documented :-) [quote] Even in a raw literal, quotes can be escaped with a backslash, but the backslash remains in the result; for example, r"\"" is a valid string literal consisting of two characters: a backslash and a double quote; r"\" is not a valid string literal (even a raw string cannot end in an odd number of backslashes). [/quote] https://docs.python.org/3/reference/lexical_analysis.html#literals
Raw strings aren't quite fully raw, which is why you can't use raw strings for Windows paths: path = r'somewhere\some\folder\' doesn't work. The reason is that "raw" (semi-cooked?) strings are s/are/were/ intended for regexes[.]
With all due respect to Steve d'A, I think that reason is inaccurate (at least in MacPorts' Python 3.8.2). I get
>>> path = r'somewhere\some\folder\' File "<stdin>", line 1 path = r'somewhere\some\folder\' ^ SyntaxError: EOL while scanning string literal
The reason for that, I believe, is that the rightmost "'" is quoted, and there is no "'" terminating the string literal.
Yes, that's what I meant when I said "it doesn't work". And the reason it doesn't work, as I understand it, is that raw strings were designed for use in regular expressions. Regexes cannot end in an odd number of backslashes. -- Steven