From: ara.t.howard@...
Date: 2006-04-13T22:40:59+09:00
Subject: Re: Range#size

On Thu, 13 Apr 2006, Meinrad Recheis wrote:

> dear list,
>
> does anyone object to adding the method :size to class Range?
>
> class Range
> 	def size
> 		max-min+1
> 	end
> end
>
> i think it's useful. maybe others too. i'd like to see it added to the core.
> here is the test for Range#size in case it's really added.
>
> def test_range_size
> 	assert_equal 1, (1..1).size
> 	assert_equal 2, (1..2).size
> 	assert_equal 3, (1..3).size
> 	assert_equal 0, (1..1).size
> 	assert_equal 1, (1...2).size
> end
>
> what do you think?
> -- henon

this has been discussed before.  the main issue is that ranges are not
sequences, but merely endpoints.

consider:

   (0.0 ... 1.0).size                    #=> Infinite, but how to compute?

   (0.0 ... 1).size                      #=> ?

   (Rational(5,6) .. Rational(5,7)).size #=> ?


   infinity = Float::MAX/Float::EPSILON
   (42.0 ... infinity).size              #=> Infinite too


   a = Gem::Version.new '0.1.0'
   b = Gem::Version.new '0.42.0'
   (a .. b ).size                       #=> potentially Infinite


   (42 .. -1).size                      #=> this is a valid range


if ranges are required to be continuous and bounded they become less useful.

i think last time someone suggested an entirely new class...

regards.

-a
-- 
be kind whenever possible... it is always possible.
- h.h. the 14th dali lama