Question

Hi all. I've been doing pset 9 and have read the documentation on __iter__ but still don't understand how it works. Instead of being an iterator, I'm just using this as a function, which I think is incorrect. Can somebody explain __iter__ and, if it's related, next() [I didn't understand how Prof Grimson used towards the end of lec 16]?

This is the first, defining __iter__. But unlike what it says in the triple quotes, I return a whole list instead of a single shape:
http://dpaste.com/589943/

The second, findLargest, is how I've used __iter__: http://dpaste.com/589942/

Thanks

Answer 1

Ok, so basically __iter__ is a method that must return an iterator for your object. What is being iterated is entirely up to you.

An iterator is just an object that has a next() method which returns different items as it is iterated. It may also raise certain iterator exceptions.

The problem with your __iter__ method is that you're actually doing the iteration there.. Also do not use __iter__ directly. If you want an iterator, use the iter builtin function:

e.g.: iter(shapes)
NOT: shapes.__iter__()