[Python-Dev] bool(iter([])) changed between 2.3 and 2.4

Guido van Rossum guido at python.org
Thu Sep 22 17:23:19 CEST 2005

On 9/22/05, Jim Jewett <jimjjewett at gmail.com> wrote:
> "Is there anything left?" is a pretty analogy for iterators,

But unmaintainable for iterators in general. This was considered ad
nauseam when iterators were initially introduced, and it was an
explicit decision *not* to provide an API to look ahead.

We should *not* give people a way to start coding like this:

  while it:
      x = it.next()
      ...process x...

when they should be writing this instead:

  for x in it:
      ...process x...

How would you implement the "is there anything left" functionality if
the iterator is in fact a generator? (I know, the answer is buffering.
But that has problems too. It was all considered when we designed it.)

--Guido van Rossum (home page: http://www.python.org/~guido/)

More information about the Python-Dev mailing list