From: Robert Klemme <shortcutter@...>
Date: 2010-05-17T23:48:26+09:00
Subject: Re: Range on strings.

2010/5/17 David A. Black <dblack@rubypal.com>:
> Hi --
>
> On Fri, 14 May 2010, Vikrant Chaudhary wrote:
>
>> Hi,
>> If I do -
>>
>> ('A'..'Z').include?('AA')
>>
>> It returns "true", while
>>
>> ('A'..'Z').to_a.include?('AA')
>>
>> (of course) returns "false". Is it intentional or possibly a bug?
>> I'm using ruby 1.8.7 (2010-01-10 patchlevel 249) [x86_64-linux] on
>> Ubuntu 10.04 x64
>
> As per the other answers, it's because ('A'..'Z').to_a is an array of
> discrete values, whereas ('A'..'Z') is a range with a start and end.
> I'll just add that in Ruby 1.9, things have changed so that include?
> on a range is, I think, the same as .to_a.include? and the behavior of
> the old include? is found in Range#cover?
>
> $ ruby191 -e 'p(("A".."Z").include?("AA"))'
> false
> $ ruby191 -e 'p(("A".."Z").cover?("AA"))'
> true
>
> include? is also available under the name member?, which I think is a
> little clearer (both because include? used to mean something else, and
> because being a "member" of a range doesn't really make sense so it
> almost has to mean something other than just being within the range).

Throwing just my cent in here: I believe the solution in 1.9.* is
better because here behavior of #include? is consistent with other
collection types: e.include?(x) == true <=> e.any? {|y| x == y} in
other words, #include? is true only if the element is also seen during
iteration.

Kind regards

robert

-- 
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/