From: ara.t.howard@...
Date: 2007-02-21T13:37:29+09:00
Subject: Re: Range#overlap?

On Wed, 21 Feb 2007, Gregory Brown wrote:

> On 2/20/07, Suraj Kurapati <snk@gna.org> wrote:
>> unknown wrote:
>> > I think that overlap? and within? are two different things, which I'm
>> > not sure you think from your email. Overlap? suggests, to me, that a
>> > subset of the things one range includes is the same as a subset of
>> > things that the other range includes. Within? suggests that all of one
>> > range is contained in a subset of the other range.
>> 
>> Agreed. These terms evoke the following synonyms in my mind:
>> 
>>   overlap?   means   intersect?
>> 
>>   within?    means   subset?
>
> These are much better names, I think.  Of course, it'll only be so if
> you are mathematically inclined.
>

indeed.

overlaps would normally be defined as

   def overlap? other
     first < other.last and other.first < last
   end

in math is always means 'proper subset'.  in otherwords

   (0..42).overlap? (1..10) #=> true
   (1..10).overlap? (0..42) #=> true


ignoring issues of inclusive and exclusive end which, i might add, all the
presented implimentations do as well.

regards.

-a
-- 
we can deny everything, except that we have the possibility of being better.
simply reflect on that.
- the dalai lama