[Python-ideas] Add peekline(), peeklines(n) and optional maxlines argument to readlines()
Nick Coghlan
ncoghlan at gmail.com
Fri Sep 30 13:28:19 CEST 2011
On Fri, Sep 30, 2011 at 5:42 AM, Giampaolo Rodolà <g.rodola at gmail.com> wrote:
> ...or 2 in case you're not at the beginning of the file.
> before = f.tell()
> f.peeklines(10)
> f.seek(before)
A context manager to handle the tell()/seek() may be an interesting
and more general purpose idea:
# In the io module
class _TellSeek:
def __init__(self, f):
self._f = f
def __enter__(self):
self._position = self._f.tell()
def __exit__(self, *args):
self._f.seek(self._position)
def restore_position(f):
return _TellSeek(f)
# Usage
with io.restore_position(f):
for i, line in enumerate(f, 1):
# Do stuff
if i == 10:
break
else:
# Oops, didn't get as many lines as we wanted
Cheers,
Nick.
--
Nick Coghlan | ncoghlan at gmail.com | Brisbane, Australia
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