Strange behaviour with os.linesep
Jason Swails
jason.swails at gmail.com
Tue Jul 23 08:39:59 EDT 2013
On Tue, Jul 23, 2013 at 7:42 AM, Vincent Vande Vyvre <
vincent.vandevyvre at swing.be> wrote:
> On Windows a script where de endline are the system line sep, the files
> are open with a double line in Eric4, Notepad++ or Gedit but they are
> correctly displayed in the MS Bloc-Notes.
>
> Example with this code:
> ------------------------------**----------------
> # -*- coding: utf-8 -*-
>
> import os
> L_SEP = os.linesep
>
> def write():
> strings = ['# -*- coding: utf-8 -*-\n',
> 'import os\n',
> 'import sys\n']
> with open('writetest.py', 'w') as outf:
> for s in strings:
> outf.write(s.replace('\n', L_SEP))
>
I must ask why you are setting strings with a newline line ending only to
replace them later with os.linesep. This seems convoluted compared to
doing something like
def write():
strings = ['#-*- coding: utf-8 -*-', 'import os', 'import sys']
with open('writetest.py', 'w') as outf:
for s in strings:
outf.write(s)
outf.write(L_SEP)
Or something equivalent.
If, however, the source strings come from a file you've created somewhere
(and are loaded by reading in that file line by line), then I can see a
problem. DOS line endings are carriage returns ('\r\n'), whereas standard
UNIX files use just newlines ('\n'). Therefore, if you are using the code:
s.replace('\n', L_SEP)
in Windows, using a Windows-generated file, then what you are likely doing
is converting the string sequence '\r\n' into '\r\r\n', which is not what
you want to do. I can imagine some text editors interpreting that as two
endlines (since there are 2 \r's). Indeed, when I execute the code:
>>> l = open('test.txt', 'w')
>>> l.write('This is the first line\r\r\n')
>>> l.write('This is the second\r\r\n')
>>> l.close()
on UNIX and open the resulting file in gedit, it is double-spaced, but if I
just dump it to the screen using 'cat', it is single-spaced.
If you want to make your code a bit more cross-platform, you should strip
out all types of end line characters from the strings before you write
them. So something like this:
with open('writetest.py', 'w') as outf:
for s in strings:
outf.write(s.rstrip('\r\n'))
outf.write(L_SEP)
Hope this helps,
Jason
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