On Mon, Jul 27, 2015 at 12:12 PM, Steven D'Aprano <steve@pearwood.info> wrote:
Being a special case, you can only use this for iterables that have an items() method. You can't do:
for k:v in [(1, 'a'), (2, 'b')]: ...
because the list doesn't have an items() method.
Here's a crazy alternative: Generalize it to subsume the common use of enumerate(). Iterate over a dict thus: for name:obj in globals(): # do something with the key and/or value And iterate over a list, generator, or any other simple linear iterable thus: for idx:val in sys.argv: # do something with the arg and its position In other words, the two-part iteration mode gives you values *and their indices*. If an object declares its own way of doing this, it provides the keys and values itself; otherwise, the default is equivalent to passing it through enumerate, so you'll get sequential numbers from zero. I don't know that this is a *good* idea (for one thing, simple iteration is equivalent to the first part for a dict, but the second part for everything else), but it does give a plausible meaning to two-part iteration that isn't over a dictionary. ChrisA