In article <mailman.14101.1411042251.18130.python-l...@python.org>, Chris Angelico <ros...@gmail.com> wrote:
> On Thu, Sep 18, 2014 at 9:55 PM, cool-RR <ram.rac...@gmail.com> wrote: > > My function gets an iterable of an unknown type. I want to check whether > > it's ordered. I could check whether it's a `set` or `frozenset`, which > > would cover many cases, but I wonder if I can do better. Is there a nicer > > way to check whether an iterable is ordered or not? > > > > An iterable is always ordered. You call next() and you get the next > value. I suspect what he meant was "How can I tell if I'm iterating over an ordered collection?", i.e. iterating over a list vs. iterating over a set. Is there anything which requires an iterator to be deterministic? For example, let's say I have an iterable, i, and I do: list1 = [item for item in i] list2 = [item for item in i] am I guaranteed that list1 == list2? It will be for all the collections I can think of in the standard library, but if I wrote my own class with an __iter__() which yielded the items in a non-deterministic order, would I be violating something other than the principle of least astonishment? -- https://mail.python.org/mailman/listinfo/python-list
