Reading a Line From File Without Advancing [Pythonic Approach]

Question

What\'s a pythonic approach for reading a line from a file but not advancing where you are in the file?

For example, if you have a file of

cat1
cat2         


        

Answer 1

You could use wrap the file up with itertools.tee and get back two iterators, bearing in mind the caveats stated in the documentation

For example

from itertools import tee
import contextlib
from StringIO import StringIO
s = '''\
cat1
cat2
cat3
'''

with contextlib.closing(StringIO(s)) as f:
  handle1, handle2 = tee(f)
  print next(handle1)
  print next(handle2)

 cat1
 cat1