isInfinite isInadequate

[Andrei Alexandrescu]

On 3/12/13 11:47 AM, Steven Schveighoffer wrote:
> On Tue, 12 Mar 2013 11:25:54 -0400, deadalnix <deadalnix at gmail.com> wrote:
>
>> On Tuesday, 12 March 2013 at 10:49:57 UTC, monarch_dodra wrote:
>
>>> Having "isInfinite" can also have the advantage of protecting users
>>> from stupid calls. For example, calling "count" on an infinite range
>>> is forbidden => shifting problems from runtime to compile time is a
>>> HUGE gain.
>>>
>>
>> Clearly this is a good point. I however think that a static assert
>> within count is much better because it allow to give nicer feedback.
>> The problem with InfiniteRange is that it does gives you cryptic error
>> message like the count function do not exists.
>>
>
> Hm... is there a way to test for inifinitness without requiring to be an
> enum?
>
> Wouldn't this also be valid?
>
> if(!R.init.empty)
>
> Essentially, you can evaluate R.init.empty at compile time AND it's
> false on an uninitialized range. How can a correctly written
> non-infinite range pass that?
>
> That would make forwarding much easier, as the 'dumb' implementation
> still would result in an infinite range.

Crossed my mind a few times that fresh non-infinite ranges should be 
empty. But there's no explicit requirement stating that, and I think 
e.g. one may define a k-elements buffer backed by in-situ storage.

Andrei