I have a text file with Windows-style line terminators (\r\n) which I open in universal newlines mode (Python 2.7). I would expect the newlines attribute to be set after the first call to the readline() method, but apparently this is not the case:
>>> f=open('test_crlf', 'rU')
>>> f.newlines
>>> f.readline()
'foo\n'
>>> f.newlines
>>> f.readline()
'bar\n'
>>> f.newlines
'\r\n'
On the other hand, the newlines attribute gets set after the first call to readline() on a file with Unix-style line endings.
What is the general rule? When should I expect the newlines attribute to be set?