[Tutor] What is this an example of (and how can i use it?)

[Alan Gauld]

kevin parks wrote:

> called, and what it is an example of. I guess there are generators and 
> iterators now and it seems this might be an example of one of those new 

This is a generator expression. It is like a list comprehension (you 
know about those right?) except it doesn't create the list it just 
returns each item on demand. You could think of a list as a list 
constructed using a generator expression.

> def roundrobin(*iterables):
>     "roundrobin('ABC', 'D', 'EF') --> A D E B F C"
>     # Recipe credited to George Sakkis
>     pending = len(iterables)
>     nexts = cycle(iter(it).next for it in iterables)

note this is storing the next methods not the results of them.

>     while pending:
>         try:
>             for next in nexts:
>                 yield next()

So the yield calls the stored method and returns the result.

HTH,

Alan G.