module Forwardable::Extended

def def_modern_delegator(accessor, method, alias_ = method, args: \
    { :before => [], :after => [] }, **kwd)
  prefix, suffix, wrap = prepare_delegate(**kwd)
  args = { :before => args } unless args.is_a?(Hash)
  b = [args[:before]].flatten.compact.map(&:to_s).join(", ")
  a = [args[ :after]].flatten.compact.map(&:to_s).join(", ")
  b = b + ", " unless args[:before].nil? || args[:before].empty?
  a = ", " + a unless args[ :after].nil? || args[ :after].empty?
  alias_ = alias_.to_s.gsub(/\?$/, "") if suffix
  class_eval delegate_debug(<<-STR), __FILE__, __LINE__ - 10
    def #{alias_}#{suffix}(*args, &block)
      #{wrap}(#{prefix}#{accessor}.send(
        #{method.inspect}, #{b}*args#{a}, &block
      ))
    rescue Exception
      if !Forwardable.debug && $@ && $@.respond_to?(:delete_if)
        $@.delete_if do |source|
          source =~ %r"#{Regexp.escape(__FILE__)}"o
        end
      end
      raise
    end
  STR
end