[Python-3000] Builtin iterator type

[Guido van Rossum]

On 11/13/06, George Sakkis <george.sakkis at gmail.com> wrote:
> On 11/13/06, Guido van Rossum <guido at python.org> wrote:
>
> > As my final word, I think this is a seriously bad idea, and as you're
> > not answering my challenge about duck typing I don't think you
> > understand your own proposal.
>
> I think I do, though I can't tell the same about the reasons of your
> objections to it. In your previous reply you mentioned that I need to
> have a more technical argument to convince you, and that's why I chose
> to reply with the most technical argument, a proof of concept
> implementation that addresses your concerns about how to incorporate
> the itertools functions as methods.
>
> As for the duck typing, I mentioned already that nobody forces you to
> extend this type to make some class an iterator, as nobody forces you
> to extend dict or dictmixin to write a user-defined mapping. You may
> well start from scratch implementing just next(); if you don't plan to
> use "+", "*" or any of the itertools operations on this type,
> extending Iter is useless. If you do plan to provide these operations
> though, you may either write them from scratch every time, or extend
> Iter.
>
> I honestly fail to understand your current objections. Is my analogy
> with dictmixin flawed ? Would anything change if I named it
> "itermixin" instead of iter or Iter ? I'm ok with the idea being
> rejected, but at least I'd like to understand the reasons.

The flaw is that you're creating two categories of iterators: those
that support the various methods you're adding, and those that don't.
This means that the itertools module can't be discarded, because it is
still needed to support those operations for the iterators that don't
have them natively. Thus, you're introducing two ways of doing the
same thing -- using itertools (works for all iterators) or using the
methods (only works for iterators that inherit from your base class).

Please stop wasting everybody's time.

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