behavior of class <<

output

a's values:
value of Foo.name: bar
Foo's object ID: 70207511032180
self's object ID: 70207511031980

b's values:
value of Foo.name: bar
Foo's object ID: 70207511032180
self's object ID: 70207511031940


# Foo is the same instance everywhere across multiple instances

test.rb

class Thing

    module Foo 
      class << self
        attr_accessor :name
      end
    end


  def setFoo(val)
    Foo.name = val 
  end

  def doSomething
    puts "value of Foo.name: " + Foo.name 
    puts "Foo's object ID: " + Foo.object_id.to_s
    puts "self's object ID: " + self.object_id.to_s
  end


end

a = Thing.new
a.setFoo("bar")

b = Thing.new

puts "a's values:"
a.doSomething

puts "\nb's values:"
b.doSomething