From: Stefan Walk <stefan.walk@...>
Date: 2006-01-14T23:47:26+09:00
Subject: Re: Range#member? Oddity

dblack@wobblini.net wrote:
  > But other weirdnesses arise :-)
> 
> irb(main):019:0> ("A".."z").member?("g")
> => true
> irb(main):020:0> ("A".."z").to_a.include?("g")
> => false
> 
> 
> David
> 

IMO, the thing at fault here is that Ranges include Enumerable. From a 
mathematical POV, that's nonsense, and that's why oddities like this 
exist. Things that can be used for ranges can not used like an 
Enumarable (rational..rational, float..float), because those don't have 
#succ instance methods... and String ranges behave oddly because the 
member? checks use the <=> behaviour, and each uses succ...

Regards,
Stefan