Add ruby class methods or instance methods dynamically

I am quite new to Ruby, so still learning. I was researching quite a bit about how to add methods dynamically, and I was successful to create instance methods, but not successful when creating class methods.

This is how I generated instance methods:

  class B
    def before_method
      puts "before method"
    end

    def self.run(method)
        send :define_method, method do
          before_method
          puts "method #{method}"
        end
    end
  end

  class A < B
    run :m
    run :n
  end

Any idea about the best ways to create static methods?

My final task is to look for the best way to create "before" and "after" tasks for class methods.