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

[Guido van Rossum]

> > Maybe the xreadlines object could grow a flush() method that throws
> > away its buffer, and f.seek() could call that if there's a cached
> > xreadlines iterator?
> 
> Couldn't f.seek just decref the xreadlines object and put a NULL
> into f's pointer to the xreadlines object?

Well, that wouldn't help for code that's hanging on to the iterator.

I also just realized that having the file object point to the
xreadlines object creates a cycle, since the xreadlines object already
points to the file.  And neither participates in GC.  I guess the
xreadlines object could drop the pointer to the file once it's raised
StopIteration, as a way to ensure that this is a sink state.  Or we
could add GC support to file objects and xreadline objects (sigh).

--Guido van Rossum (home page: http://www.python.org/~guido/)