Generator using item[n-1] + item[n] memory

Nick Timkovich prometheus235 at gmail.com
Sat Feb 15 04:31:49 CET 2014


OK, now the trick; adding `data = None` inside the generator works, but in
my actual code I wrap my generator inside of `enumerate()`, which seems to
obviate the "fix".  Can I get it to play nice or am I forced to count
manually. Is that a feature?


On Fri, Feb 14, 2014 at 9:21 PM, Roy Smith <roy at panix.com> wrote:

> In article <mailman.6952.1392433921.18130.python-list at python.org>,
>  Nick Timkovich <prometheus235 at gmail.com> wrote:
>
> > Ah, I think I was equating `yield` too closely with `return` in my head.
> >  Whereas `return` results in the destruction of the function's locals,
> > `yield` I should have known keeps them around, a la C's `static`
> functions.
> >  Many thanks!
>
> It's not quite like C's static.  With C's static, the static variables
> are per-function.  In Python, yield creates a context per invocation.
> Thus, I can do
>
> def f():
>     for i in range(10000):
>         yield i
>
> g1 = f()
> g2 = f()
> print g1.next()
> print g1.next()
> print g1.next()
> print g2.next()
> print g1.next()
>
>
> which prints 0, 1, 2, 0, 3.  There's two contexts active at the same
> time, with a distinct instance of "i" in each one.
> --
> https://mail.python.org/mailman/listinfo/python-list
>
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