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

[David Abrahams]

I keep running into the problem that there is no reliable way to introspect
about whether a type supports multi-pass iterability (in the sense that an
input stream might support only a single pass, but a list supports multiple
passes). I suppose you could check for __getitem__, but that wouldn't cover
linked lists, for example.

Can anyone channel Guido's intent for me? Is this an oversight or a
deliberate design decision? Is there an interface for checking
multi-pass-ability that I've missed?

TIA,
Dave