https://twitter.com/mtsmfm/status/1133563635874189312

hi.rb

module Hi
  instance_methods_snapshot = []

  TracePoint.trace(:class) do |tp|
    next unless tp.self == self
    # Hi.singleton_class.prepend Module.new { define_method(:method_added) { "ここで最小限のスナップショットを取ることも可能" } }
    instance_methods_snapshot = instance_methods.map(&method(:instance_method))
  end

  TracePoint.trace(:end) do |tp|
    next unless tp.self == self
    instance_methods_snapshot.each do |instance_method_snapshot|
      method_name = instance_method_snapshot.name
      current_instance_method = instance_method(method_name)

      next if instance_method_snapshot == current_instance_method

      module_eval do
        define_method(method_name) do
          instance_method_snapshot.bind(self).call
          current_instance_method.bind(self).call
        end
      end
    end
  end
end

ツイート可能

module Hi
  m=nil
  TracePoint.trace(:class) { |tp| tp.self == self && m=instance_method(:hi) rescue nil }
  TracePoint.trace(:end) { |tp| next unless tp.self == self; (m2=instance_method(:hi) rescue nil)&.==m&.== define_method(:hi) { m.bind(self).call; m2.bind(self).call } }
end