[EMAIL PROTECTED] wrote:
now suppose I have read the first line already.
then I read the second line and notice
that there is a ">" in front (my special character)
then I want the put back the second line into the
file or the stdin.

Amended iterator class example using my peekable recipe:

>>> class strangefileiter(object):
...     def __init__(self, file):
...         self.iter = peekable(file)
...     def __iter__(self):
...         while True:
...             next = self.iter.peek()
...             if not next or next.rstrip('\n') == "|":
...                 break
...             yield self.iter.next()
...
>>> file('temp.txt', 'w').write("""\
... some text
... some more
... |
... not really text""")
>>> f = strangefileiter(file('temp.txt'))
>>> for line in f:
...     print repr(line)
...
'some text\n'
'some more\n'
>>> remainder = f.iter
>>> for line in remainder:
...     print repr(line)
...
'|\n'
'not really text'

Note that because I wrap the file iterator with a peekable[1] object, the lines aren't consumed when I test them. So to access the remaining lines, I just use the iter field of the strangefileiter object.

Steve

[1] http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/304373
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