From: Dave Thomas <dave@...>
Date: 2008-03-27T05:29:21+09:00
Subject: Re: Recent changes in Range#step behavior

Gabon:

You'd still have

t3.between? t1, t2

And you'd still have

t1..t2.cover t3


So it seems you're covered

Cheers


Dave

On Mar 26, 2008, at 3:02 PM, "Gavin Kistner" <gavin.kistner@anark.com>  
wrote:

> From: Dave Thomas [mailto:dave@pragprog.com]
>> The anomaly is ranges of floats, which you aren't allowed to iterate
>> anyway. In that case, member? becomes a comparison that the argument
>> is between the limit, because conceptually the range (1.0..2.0)
>> contains the infinite number of real values between 1 and 2.
>
> I've occasionally found it convenient to use a single Range of Time
> values, to be able to determine if a time falls in the middle of  
> them. A
> range of Times would not, I think, be considered discrete.
>
> I would be sad (and confused) if this behavior changed:
>
> irb(main):006:0> t1 = Time.now
> => Wed Mar 26 13:59:15 -0600 2008
> irb(main):007:0> t2 = t1 + 10
> => Wed Mar 26 13:59:25 -0600 2008
> irb(main):008:0> t3 = t1 + 5.5
> => Wed Mar 26 13:59:21 -0600 2008
> irb(main):009:0> (t1..t2).include?( t3 )
> => true
>
> ...despite the fact that Time#succ is defined and happens to step
> forward 1 second at a time.
>
> I ask for validating arguments to the claim that a range is a set of
> discrete elements. I contend that it is only discrete once it is
> actually expanded/iterated. It seems more appropriate to have
> my_range.to_set.include?( foo ) when you truly want to talk about set
> membership.
>