Public.System.FSEvents is a Pike module that provides an interface to FSEvents. 
FSEvents is an API in Mac OS X which allows an application to register for 
notifications of changes to a given directory tree without forcing the 
application to continously poll the directory tree.

This module is designed for use in asynchronous or backend mode, that is, 
rather than polling for changes, a function you specify will be called when 
events of interest occur. This module assumes the presence and use of
a CFRunLoop based Backend object, otherwise this module will not receive
events from the OS. The CFRunLoop Backend is a new feature that is available 
in development versions of Pike 7.9.6 and greater running on Mac OS X 10.5 and 

See the examples directory for a sample script that prints out events for 
a given directory, as they occur.