From: Dale Martenson <dmartenson@...>
Date: 2002-03-26T11:25:03+09:00
Subject: RE: File change notification?

>> Is there a straightforward way of getting notified when a file
>> changes? In NT I can block a thread on the handle returned by
>> FindFirstChangeNotification. Does something like this exist in Ruby?
>> I'm currently using the Cygwin version but could be convinced to
>> switch.

Here is a little hack that might work for you. There may be a better way,
but I am still learning Ruby myself.

class FileCheck < Thread
  def initialize( filename, callback, checktime=2 )
    currentModTime = File.stat(filename).mtime
    return super {
      while true
        if currentModTime < File.stat(filename).mtime then
          callback.call
	  currentModTime = File.stat(filename).mtime
        end
        sleep(checktime)
      end
    }
  end  
end

# Do this when the file changes
def fcAction
  print "#{Time.now}: Something changed!!\n"
end

# Create a file check on the passed in argument
fc = FileCheck.new( ARGV.shift, proc { fcAction } )
fc.run

# do something useful for a while (hopefully not this)
while true
  print "#{Time.now}: Nothing yet.\n"
  sleep(3)
end