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

[Guido van Rossum]

> The real reason to be able to introspect is so that you can handle both
> kinds.
> Even if you're willing to destroy the data by examining it, if you know you
> have a single-pass sequence, you might need to copy its elements into a
> multi-pass sequence (e.g. file.lines()) in order to get your work done.

Hm.  I think it's just as good to make it the responsibility of the
caller to pass a multi-iterable.  There could be a standard tool that
takes a single-iterable and produces a multi-iterable.

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