method_caller_logger.rb

module MethodCallerLogger
  module ClassMethods
    LOG_FORAMT = "%s at %s:L%s"

    def parse_caller(_caller)
      if /^(.+?):(\d+)(?::in `(.*)')?/ =~ _caller
        file = $1
        line = $2.to_i
        method = $3
        [file, line, method]
      end
    end

    def log_call_point(_caller)
      file, line, method = parse_caller(_caller[0])
      message = sprintf(LOG_FORAMT, method, file, line)
      warn message
    end
  end

  def self.included(base)
    base.extend(ClassMethods)

    base.class_eval do 
      defined_instance_methods = base.instance_methods(false)

      defined_instance_methods.each do |method|
        method_with_logger = (method.to_s + "_with_logger").to_sym
        method_without_logger = (method.to_s + "_without_logger").to_sym

        define_method(method_with_logger) do |*args|
          self.class.log_call_point(caller)
          __send__ method_without_logger, *args
        end

        alias_method method_without_logger, method
        alias_method method, method_with_logger
      end

      singleton_class = (class << base; self end)
      defined_class_methods = singleton_class.instance_methods(false)

      defined_class_methods.each do |method|
        method_with_logger = (method.to_s + "_with_logger").to_sym
        method_without_logger = (method.to_s + "_without_logger").to_sym
        singleton_class.class_eval do
          define_method(method_with_logger) do |*args|
            self.log_call_point(caller)
            __send__ method_without_logger, *args
          end

          alias_method method_without_logger, method
          alias_method method, method_with_logger
        end
      end
    end
  end
end