static variables in ruby

Question

i just learned about static variables in php.. i was just wondering is there any thing like that in ruby...

say..

if we want to create a student class and for each student(object) we create, its id no should get incremented automatically..

I thought creating class variable as a static will do...

thanks,

regards, levirg

Answer 1

Class variables are shared between all instances (which is why they're called class variables), so they will do what you want. They're also inherited which sometimes leads to rather confusing behavior, but I don't think that will be a problem here. Here's an example of a class that uses a class variable to count how man instances of it have been created:

class Foo
  @@foos = 0

  def initialize
    @@foos += 1
  end

  def self.number_of_foos
    @@foos
  end
end

Foo.new
Foo.new
Foo.number_of_foos #=> 2