unable to comment out r'\u' string with triple quote marks

[ElmarBucher]

BPO	40250
Nosy	@ericvsmith, @vedgar

^{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 2022-01-23.19:13:47.139>
created_at = <Date 2020-04-10.23:03:11.676>
labels = ['interpreter-core', 'invalid', 'build', '3.7']
title = "unable to comment out r'\\u' string with triple quote marks"
updated_at = <Date 2022-01-23.19:13:47.139>
user = 'https://bugs.python.org/ElmarBucher'

bugs.python.org fields:

activity = <Date 2022-01-23.19:13:47.139>
actor = 'iritkatriel'
assignee = 'none'
closed = True
closed_date = <Date 2022-01-23.19:13:47.139>
closer = 'iritkatriel'
components = ['Interpreter Core']
creation = <Date 2020-04-10.23:03:11.676>
creator = 'Elmar Bucher'
dependencies = []
files = []
hgrepos = []
issue_num = 40250
keywords = []
message_count = 3.0
messages = ['366166', '366169', '366175']
nosy_count = 3.0
nosy_names = ['eric.smith', 'veky', 'Elmar Bucher']
pr_nums = []
priority = 'normal'
resolution = 'not a bug'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'compile error'
url = 'https://bugs.python.org/issue40250'
versions = ['Python 3.7']

[ElmarBucher]

When I try to comment out this little code by triple quotation,
I run into
SyntaxError: (unicode error) 'unicodeescape' codec can't decode bytes in position 29-30: truncated \uXXXX escape

ls_tex = []
ls_tex.append(r'\usepackage{mathtools}')
print(ls_tex)

Basically it is not possible to use r'\u' and comment it out with ''' or """. I think this should not be the case, this is an interpreter error.

[ericvsmith]

This basically comes down to """\u""" not being a valid string.

I'm not sure why you'd expect this to work: triple quoted strings are not designed as a general purpose "comment out" facility, and as you've discovered, they don't work that way. What's inside a triple quoted string must be interpretable as a python string, which in this case it is not.

[vedgar]

This "bug" is reported at least once a year, by different people. Maybe we should put something in the documentation, to the effect that

a) as Eric said, triple-quoted strings are not (meant to be used as) comments

b) if you nonetheless really want to use them that way, in most cases you _can_ get away with using r'''...'''.