# File lib/poll.rb, line 150
 def register( io, eventMask, callback=nil, *arguments, &block )
		raise TypeError, "#{io.class.name} does not appear to be file-descriptor-based" unless
			io.respond_to?( :fileno ) && io.fileno

		# Clear any old events for this handle
		@events.delete( io )

		# Set the mask
		@masks[ io ] = 0
		setMask( io, eventMask )

		# Set the callback
		setCallback( io, (callback||block), *arguments )
	end