[Python-Dev] More imformative iterator representations

[Raymond Hettinger]

> But... if an iterator is sufficiently random-access to be able to
> report its length and produce selected items without doing anything
> irreversible, wouldn't it make more sense for it to be a (possibly
> read-only) sequence rather than an iterator in the first place?
> 
> In other words, instead of e.g. dict.iteritems() there should be
> a dict.itemseq() or something that returns a sequence-like view
> of the dict.

Trees, dicts, and sets all know their length and can iterate
sequentially without having random access.  PyDict_Next() makes it easy
to find the first 3 keys, but there is no general purpose way of finding
the nth key without looping over them all.


Raymond