From: Rob Biedenharn <Rob@...>
Date: 2009-08-06T00:35:41+09:00
Subject: Re: Bizarre Range behavior

On Aug 5, 2009, at 12:55 AM, Yukihiro Matsumoto wrote:
> Hi,
>
> In message "Re: Bizarre Range behavior"
>    on Wed, 5 Aug 2009 05:32:37 +0900, Rob Biedenharn <Rob@AgileConsultingLLC.com 
> > writes:
>
> |Knowing this, here's an even more bizzare-looking example:
> |
> |irb> "19".succ
> |=> "20"
> |irb> ("2".."19").to_a
> |=> []
> |irb> ("2"..."20").to_a
> |=> ["2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12", "13",
> |"14", "15", "16", "17", "18", "19"]
>
> What if I sprinkle more magic to the language and change String#upto
> to generate numerical sequences when all characters in edges are
> digits, so that
>
> irb> ("2".."19").to_a
> => ["2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12", "13",  
> "14", "15", "16", "17", "18", "19"]
> irb> ("2"..."20").to_a
> => ["2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12", "13",  
> "14", "15", "16", "17", "18", "19", "20"]
>
> Any opinion?  I already made a patch for trunk.
>
> 							matz.


I'd actually prefer *less* magic here. (And I hope that your second  
example with "2"..."20" wouldn't include "20" since the range excludes  
its end.)

The surprising aspect is that the Range#to_a can give an array that  
has just the #begin. String#upto perhaps needs more magic to know that  
#succ will eventually work ("9".upto("10") as well as  
"cat".upto("bird"))

-Rob

Rob Biedenharn		http://agileconsultingllc.com
Rob@AgileConsultingLLC.com