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

[Guido van Rossum]

> > Can you remind me of your definition of "iterable"?  Mine is
> > "something for which iter() works", which clearly isn't yours. :-)
> 
> Right -- I mean something closer to what I've seen others call
> "a container".  By your definition, iterators are indeed iterable.
> I would love for all iterables-by-your-definition to divide neatly
> into iterators and what-many-call-containers.
> 
> The file object, unless you make it into an iterator, is not "a
> container" like all others and just sits there -- a bit of a wart.

I must be misunderstanding.  How does making the file object into an
iterator make it a container???

> > > f.seek does cooperate with f.next now, doesn't it?  since it
> > > invalidates f's xreadlines object, if any?
> >
> > Not yet.  You may have seen Oren's patch for this.  Unfortunately it
> 
> Right -- that's what I had in mind.  I had also tweaked it so that
> readline sort of interoperated with it (delegating to next if the file
> object is holding an xreadlines object) and sent the modified patch
> to Oren but he disliked it (because it meant readline would not
> respect its numeric argument, if any, in that case).

Hm, you should've sent it to me.  The numeric argument was a mistake I
think.  Who ever uses it?

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