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From: ram@zedat.fu-berlin.de (Stefan Ram)
Newsgroups: comp.lang.python
Subject: Re: Lengthy numbers
Date: 23 Dec 2024 08:02:08 GMT
Organization: Stefan Ram
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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!