What is the purpose in Python's itertools.repeat?

Question

Every use I can think of for Python\'s itertools.repeat() class, I can think of another equally (possibly more) acceptable solution to achieve the same effect. For example:<

Answer 1

Your example of foo * 5 looks superficially similar to itertools.repeat(foo, 5), but it is actually quite different.

If you write foo * 100000, the interpreter must create 100,000 copies of foo before it can give you an answer. It is thus a very expensive and memory-unfriendly operation.

But if you write itertools.repeat(foo, 100000), the interpreter can return an iterator that serves the same function, and doesn't need to compute a result until you need it -- say, by using it in a function that wants to know each result in the sequence.

That's the major advantage of iterators: they can defer the computation of a part (or all) of a list until you really need the answer.