From: "Peña, Botp" <botp@...>
Date: 2008-06-28T16:46:34+09:00
Subject: Re: Determining lists,strings and numbers(Newbie question)

From: vimal [mailto:cool.vimalsmail@gmail.com] 
# How can one determine whether a given object is a list or string or
# number

botp@botp-desktop:~$ qri object.is_a?
----------------------------------------------------------- Object#is_a?
     obj.is_a?(class)       => true or false
     obj.kind_of?(class)    => true or false
------------------------------------------------------------------------
     Returns true if class is the class of obj, or if class is one of
     the superclasses of obj or modules included in obj.

        module M;    end
        class A
          include M
        end
        class B < A; end
        class C < B; end
        b = B.new
        b.instance_of? A   #=> false
        b.instance_of? B   #=> true
        b.instance_of? C   #=> false
        b.instance_of? M   #=> false
        b.kind_of? A       #=> true
        b.kind_of? B       #=> true
        b.kind_of? C       #=> false
        b.kind_of? M       #=> true


irb(main):001:0> "asdf".is_a? String
=> true
irb(main):002:0> "asdf".is_a? Integer
=> false
irb(main):003:0> 1.is_a? Integer
=> true
irb(main):004:0> 1.is_a? Array
=> false
irb(main):005:0> ["",1].is_a? Array
=> true