[Python-Dev] [Python-ideas] Expose `itertools.count.start` and implement `itertools.count.__eq__` based on it, like `range`.

[Nick Coghlan]

On 7 June 2014 19:36, Ram Rachum <ram.rachum at gmail.com> wrote:
> My need is to have an infinite immutable sequence. I did this for myself by
> creating a simple `count`-like stateless class, but it would be nice if that
> behavior was part of `range`.

Handling esoteric use cases like it sounds yours was is *why* user
defined classes exist. It does not follow that "I had to write a
custom class to solve my problem" should lead to a standard library or
builtin changing unless you can make a compelling case for:

* the change being a solution to a common problem that a lot of other
people also have. "I think it might be nice" and "it would have been
useful to me to help solve this weird problem I had that one time"
isn't enough.
* the change fitting in *conceptually* with the existing language and
tools. In this case, "infinite sequence" is a fundamentally incoherent
concept in Python - len() certainly won't work, and negative indexing
behaviour is hence not defined. By contrast, since iterables and
iterators aren't required to support len() the way sequences are,
infinite iterable and infinite iterator are both perfectly well
defined.

Cheers,
Nick.

-- 
Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia