Static variables in ruby, like in C functions

Question

Is there any such thing as static variables in Ruby that would behave like they do in C functions?

Here\'s a quick example of what I mean. It prints \"6\\n7\\n\" to the

Answer 1

Use a variable in the singleton class (The static class itself)

class Single
  def self.counter
    if @count  
      @count+=1
    else
      @count = 5
    end
  end
end

In ruby, any class is an object which has only one instance. Therefore, you can create an instance variable on the class, and it will work as a "static" method ;)

Output:

  ruby 2.5.5p157 (2019-03-15 revision 67260) [x86_64-linux]

=> :counter
   Single.counter
=> 5
   Single.counter
=> 6
   Single.counter
=> 7

To get this behaviour on the main scope, you can do:

module Countable
  def counter
    if @count  
      @count+=1
    else
      @count = 5
    end
  end
end

=> :counter
   self.class.prepend Countable # this "adds" the method to the main object
=> Object
   counter
=> 5
   counter
=> 6
   counter
=> 7