From: Bill Walton <bill.walton@...>
Date: 2008-07-25T02:14:25+09:00
Subject: Re: differnce between .nil? , .empty?, .blank?

Hi Marc,

Marc Heiler wrote:

> Isn't .nil? and .empty? in a way testing for a very similar
> situation?

Not in Ruby.  empty? is true for a String of length 0.  The value of the
String is not Nil.  It turns out that Nil is very important in evaluations
since it's one of the two items in Ruby that evaluates to false.

irb(main):001:0> str = String.new
=> ""
irb(main):002:0> str.length
=> 0
irb(main):003:0> if str then puts 'a zero-length string is still a string'
end
a zero-length string is still a string
=> nil
irb(main):004:0> str = nil
=> nil
irb(main):005:0> if str.nil? then puts 'assigning a nil value essentially
kills
the object' end
assigning a nil value essentially kills the object
=> nil.

HTH,
Bill