[Python-ideas] Allow __len__ to return infinity

[Ram Rachum]

This actually makes me think that `range(int('inf'))` is a more elegant
construct than `itertools.count()`. Also `range(x, int('inf'))`
for `itertools.count(x)`, and then you have `range(x, int('inf'), y)`
or `range(0, int('-inf'), -1)` which `itertools.count` can't cover.

On Tue, Feb 25, 2014 at 1:46 PM, Paul Moore <p.f.moore at gmail.com> wrote:

> On 25 February 2014 11:18, Steven D'Aprano <steve at pearwood.info> wrote:
> > (1) __len__ can return *any* float, regardless of value, including
> > lengths of 0.5, NAN, 1e300, etc. This is undesirable because lengths of
> > sequences should be positive or zero whole numbers, not arbitrary
> > floating point values like 4.5.
> >
> > (2) __len__ cannot return any float, but only INF. Which means that the
> > condition that len() only returns ints will be broken in the most
> > surprising way, with a single exception.
>
> Either of these would break range(len(x)) at a minimum, and probably
> most other code that uses len(). So you'd be left with code having to
> identify "objects that only return finite len" and "objects that could
> have one of the new len values". And if the OP can detect that, he can
> just do so in his code and special case his objects, rather than
> changing the len protocol.
>
> Paul
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