class Spring::Watcher::Abstract

watcher.stale? # => true<br>IO.select() # watcher is running in background
watcher = MyWatcher.new(root, latency)
A user of a watcher can use IO.select to wait for changes:

def add(*items) 

def add(*items)
  items = items.flatten.map do |item|
    item = Pathname.new(item)
    if item.relative?
      Pathname.new("#{root}/#{item}")
    else
      item
    end
  end
  items = items.select(&:exist?)
  synchronize {
    items.each do |item|
      if item.directory?
        directories << item.realpath.to_s
      else
        files << item.realpath.to_s
      end
    end
    subjects_changed
  }
end

def initialize(root, latency) 

def initialize(root, latency)
  super()
  @root        = File.realpath(root)
  @latency     = latency
  @files       = Set.new
  @directories = Set.new
  @stale       = false
  @listeners   = []
end

def mark_stale 

def mark_stale
  return if stale?
  @stale = true
  @listeners.each(&:call)
end

def on_stale(&block) 

def on_stale(&block)
  @listeners << block
end

def restart 

def restart
  stop
  start
end

def stale? 

def stale?
  @stale
end

def start 

def start
  raise NotImplementedError
end

def stop 

def stop
  raise NotImplementedError
end

def subjects_changed 

def subjects_changed
  raise NotImplementedError
end