[Python-3000] Making more effective use of slice objects in Py3k (original) (raw)

Josiah Carlson jcarlson at uci.edu
Tue Aug 29 18:24:29 CEST 2006

"Guido van Rossum" <guido at python.org> wrote:

On 8/28/06, Josiah Carlson <jcarlson at uci.edu> wrote: > While there are examples where views can be slower, this is no different > than the cases where deque is slower than list; sometimes some data > structures are more applicable to the problem than others. As we have > given users the choice to use a structure that has been optimized for > certain behaviors (set and deque being primary examples), this is just > another structure that offers improved performance for some operations.

As long as it is very carefully presented as such I have much less of a problem with it. Earlier proposals were implying that all string ops should return views whenever possibe. That, I believe, is never going to fly, and that's where my main objection lies.

String operations always returning views would be arguably insane. I hope no one was recommending it (I certainly wasn't, but if my words were confusing on that part, I apologize); strings are strings, and views should only be constructed explicitly.

After you have a view, I'm of the opinion that view operations should return views, except in the case where you explicitly ask for a string via str(view).

Having views in a library module alleviates many of my objections. While I still worry that it will be overused, deque doesn't seem to be overused, so perhaps I should relax.

While it would be interesting (as a social experiment) for views to be in the builtins module (to test abuse theories), it is probably much better for it to sit in the collections module.

> > Then I ask you to make it so that string views are 99.999% > > indistinguishable from strings -- they have all the same methods, are > > usable everywhere else, etc. > > For reference, I'm about 2 hours into it (including re-reading the > documentation for Pyrex), and I've got [r]partition, [r]find, [r]index, > [r|l]strip. I don't see significant difficulty implementing all other > methods on views. > > Astute readers of the original implementation will note that I never > check that the argument being passed in is a string; I use the buffer > interface, so anything offering the buffer interface can be seen as a > read-only view with string methods attached. Expect a full > implementation later this week.

Good luck!

Thank you!

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