method_logger.rb

class MethodLogger
  def log_method(klass, method_name)
    klass.class_eval do
      alias_method "#{method_name}_original", method_name
      define_method method_name do |*args, &block|
        puts "Called #{method_name}"
        send "#{method_name}_original", *args, &block
      end
    end
  end
end