Python: range is not an iterator
After my Loop Better talk at PyGotham 2017 someone asked me a great question: iterators are lazy iterables and range is a lazy iterable in Python 3, so is range an iterator?
Unfortunately, I don’t remember the name of the person who asked me this question. I do remember saying something along the lines of “oh I love that question!”
I love this question because range objects in Python 3 (xrange in Python 2) are lazy, but range objects are not iterators and this is something I see folks mix up frequently.
In the last year I’ve heard Python beginners, long-time Python programmers, and even other Python educators mistakenly refer to Python 3’s range objects as iterators. This distinction is something a lot of people get confused about.
When people talk about iterators and iterables in Python, you’re likely to hear the someone repeat the misconception that range is an iterator. This mistake might seem unimportant at first, but I think it’s actually a pretty critical one. If you believe that range objects are iterators, your mental model of how iterators work in Python isn’t clear enough yet. Both range and iterators are “lazy” in a sense, but they’re lazy in fairly different ways.
