Oscar Benjamin <
oscar.j.benjamin@gmail.com> wrote or quoted:
x = [0]; x.extend(iter(x))
Yo, that's a gnarly piece of Python code!
This code whips up an infinite list, but in a pretty slick way.
Here's the lowdown:
- First off, we're cooking up a list x with just one ingredient: 0
- Then we're using extend() to pile more stuff onto x
- The mind-bender is what we're extending with: iter(x)
iter(x) spins up an iterator from the list x. When we extend x
with this iterator, it starts tossing the elements of x back into
itself. But here's the kicker: as x grows, the iterator keeps
chugging along, creating an endless loop.
So in theory, this would crank out an infinite list that looks like
[0, 0, 0, 0, ...]. In the real world, though, if you try to print or
use this list, your program will probably freeze up faster than the
405 at rush hour.
It's a pretty clever (and kind of diabolical) way to create an
infinite data structure. Just watch out using something like
this in actual code - it could cause some serious brain freeze!
--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)