[Python-Dev] Single- vs. Multi-pass iterability

[Andrew Koenig]

Guido> Likewise, the file needs a strong ref to the xreadlines,
Guido> otherwise the following would create a new iterator in the
Guido> second for loop, and lose data buffered by the first iterator.

Guido>     f = open(filename)
Guido>     it = iter(f)
Guido>     for i in range(10):
Guido>         it.next()
Guido>     del it
Guido>     for line in f:
Guido>         print line,

Guido> I think I will have to reject Oren's patch because of this, and
Guido> the situation with file iterators will remain as it is: once
Guido> you've asked for the iterator, all operations on the file are
Guido> unsafe, and the only way to get back to using the file is to
Guido> abandon the file and do an absolute seek on the file.

This implies that you don't expect the code above to work correctly, right?

-- 
Andrew Koenig, ark@research.att.com, http://www.research.att.com/info/ark