A escape character is used when a REGEXP is an argument of "strip" string function

[TitoBouzout]

BPO	21283
Nosy	@ericvsmith, @ezio-melotti

^{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 = None
closed_at = <Date 2014-04-17.14:50:33.441>
created_at = <Date 2014-04-17.13:54:45.391>
labels = ['type-bug', 'invalid']
title = 'A escape character is used when a REGEXP is an argument of "strip" string function'
updated_at = <Date 2014-04-21.13:30:18.872>
user = 'https://bugs.python.org/TitoBouzout'

bugs.python.org fields:

activity = <Date 2014-04-21.13:30:18.872>
actor = 'Tito.Bouzout'
assignee = 'none'
closed = True
closed_date = <Date 2014-04-17.14:50:33.441>
closer = 'eric.smith'
components = []
creation = <Date 2014-04-17.13:54:45.391>
creator = 'Tito.Bouzout'
dependencies = []
files = []
hgrepos = []
issue_num = 21283
keywords = []
message_count = 4.0
messages = ['216687', '216688', '216694', '216944']
nosy_count = 4.0
nosy_names = ['eric.smith', 'ezio.melotti', 'mrabarnett', 'Tito.Bouzout']
pr_nums = []
priority = 'normal'
resolution = 'not a bug'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue21283'
versions = ['Python 3.3']

[TitoBouzout]

Hello!

I got a report that the character "\" was removed from a string using the following code

"\\server\path\to".strip(r'"\'<>')

At first insight, looks like a bug, because I don't expect the use of the escape character at all. Then I noticed, that our mistake there is that the "strip" argument should be a "string" not a REGEXP.

Kinda weird to read, and I've no idea if this is expected behaviour in Python, as I'm relatively very new. So just informing,

Kind regards,

--
Tito

[mrabarnett]

The argument isn't a regex, it's a raw string literal consisting of the characters " (quote), \ (backslash), ' (apostrophe), < (less than) and > (greater than).

[ericvsmith]

In addition, you probably want "\\server\path\to" to be a raw string, too. That way, the backslashes are not given special meaning. Notice the difference in output between these two:

>>> "\\server\path\to".strip(r'"\'<>') 
'server\\path\to'
>>> r"\\server\path\to".strip(r'"\'<>') 
'server\\path\\to'

In the first one, '\t' is being treated as a tab character, in the second one you see a backslash followed by a 't'.

My rule of thumb is: any time you have a string with a filename containing backslashes, you want it to be a raw string.

[TitoBouzout]

Thanks guys for the information! Is still weird to me that the escape character is used, but well ! Will remember this bug.
Kind regards,