textwrap.dedent doesn't work properly with embedded strings containing linefeeds

[mdear]

BPO	23497
Nosy	@ned-deily

^{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 2015-02-22.01:19:25.975>
created_at = <Date 2015-02-22.00:57:55.125>
labels = ['invalid']
title = "textwrap.dedent doesn't work properly with embedded strings containing linefeeds"
updated_at = <Date 2015-02-22.01:19:25.834>
user = 'https://bugs.python.org/mdear'

bugs.python.org fields:

activity = <Date 2015-02-22.01:19:25.834>
actor = 'ned.deily'
assignee = 'none'
closed = True
closed_date = <Date 2015-02-22.01:19:25.975>
closer = 'ned.deily'
components = []
creation = <Date 2015-02-22.00:57:55.125>
creator = 'mdear'
dependencies = []
files = []
hgrepos = []
issue_num = 23497
keywords = []
message_count = 2.0
messages = ['236396', '236398']
nosy_count = 2.0
nosy_names = ['ned.deily', 'mdear']
pr_nums = []
priority = 'normal'
resolution = 'not a bug'
stage = 'resolved'
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue23497'
versions = []

[mdear]

The textwrap.dedent function does not work when the string to dedent itself contains embedded strings that contain newline characters.

https://docs.python.org/3.4/library/textwrap.html?highlight=dedent#textwrap.dedent states that this function "can be used to make triple-quoted strings line up with the left edge of the display".

It just so happens that my triple-quoted string itself contains a single-quoted string with newline characters. I would have expected textwrap.dedent to ignore these newline characters inside single or double quoted strings contained in the larger triple-quoted string.

The semantics of this bug may be slightly different than https://bugs.python.org/issue19479 "textwrap.dedent doesn't work properly with strings containing CRLF", so I'm raising a new issue.

I am seeing this in a module I'm writing that emits synthetic python code that is subsequently passed back into the interpreter via "exec".

Python 3.4.1 (default, Nov 12 2014, 13:34:29) 
[GCC 4.1.2 20080704 (Red Hat 4.1.2-48)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from textwrap import dedent
>>> s = '''
...     'my_key' : r'my value which contains \n character'
... '''
>>> s
"\n    'my_key' : r'my value which contains \n character'\n"
>>> dedent(s)
"\n   'my_key' : r'my value which contains \ncharacter'\n"
>>>

[ned-deily]

If you do not want the \n to be interpreted as a linefeed, you need to use a raw string literal, like:

a = r'''
...     'my_key' : r'my value which contains \n character'
... '''
>>> print(dedent(a))

'my_key' : r'my value which contains \n character'