Python 2.7 splitlines fails to split over trailing backslash

Question

Using Python 2.7.9, I'm trying to take a DOS-style directory listing and split it into separate lines using the built-in splitlines function. The listing is of a directory, and one of the lines in my triple-quoted string contains a trailing backslash. The problem is that the line ending with a backslash is not being split:

# DOS-style listing of the directory "B:\"
listing = """Directory of B:\
            12/15/2014  02:12 PM             1814814 BIRD.LOG
            01/01/2000  12:04 AM    <DIR>            CONFIG
            12/15/2014  02:55 PM               35060 ALLIGATOR.LOG
            03/15/2013  02:06 PM    <DIR>            MONKEY
            03/15/2013  02:06 PM    <DIR>            FROG
            03/15/2013  02:06 PM    <DIR>            BADGER
                2 File(s)    1849874 bytes
                4 Dir(s)     1674739712 bytes free
"""

# BIRD.LOG is combined with prior line ending in a backslash
print "keepends = False"
for line in listing.splitlines(False): print repr(line)

# Setting keepends=True does not help
print "keepends = True"
for line in listing.splitlines(True): print repr(line)

Here is the output:

keepends = False
'Directory of B:          12/15/2014  02:12 PM             1814814 BIRD.LOG'
'          01/01/2000  12:04 AM    <DIR>            CONFIG'
'          12/15/2014  02:55 PM               35060 ALLIGATOR.LOG'
'          03/15/2013  02:06 PM    <DIR>            MONKEY'
'          03/15/2013  02:06 PM    <DIR>            FROG'
'          03/15/2013  02:06 PM    <DIR>            BADGER'
'              2 File(s)    1849874 bytes'
'              4 Dir(s)     1674739712 bytes free'
keepends = True
'Directory of B:          12/15/2014  02:12 PM             1814814 BIRD.LOG\n'
'          01/01/2000  12:04 AM    <DIR>            CONFIG\n'
'          12/15/2014  02:55 PM               35060 ALLIGATOR.LOG\n'
'          03/15/2013  02:06 PM    <DIR>            MONKEY\n'
'          03/15/2013  02:06 PM    <DIR>            FROG\n'
'          03/15/2013  02:06 PM    <DIR>            BADGER\n'
'              2 File(s)    1849874 bytes\n'
'              4 Dir(s)     1674739712 bytes free\n'

The problem is unchanged passing keepends = True. The Python splitlines documentation does not mention any special handling of backslashes, and neither does the documentation for the universal newlines approach to splitting lines.

My code sample is from a unit test, but in the real world the listing will be retrieved programmatically. I can think of workarounds involving manipulating my input listing or other methods, but I'm wondering why a workaround should be necessary at all. Is it a bug? Any advice would certainly be appreciated!

Answer 1

The problem with your unit test is that the \ character in your string literal is interpreted as an escape character by Python. Try changing the first line to

listing = r"""Directory of B:\

From the Python docs:

String literals may optionally be prefixed with a letter 'r' or 'R'; such strings are called raw strings and use different rules for interpreting backslash escape sequences.

In a real work scenario where you get the string from a command output, this should not be a problem.