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IO::Select(3pm) 		 Perl Programmers Reference Guide		  IO::Select(3pm)

       IO::Select - OO interface to the select system call

	   use IO::Select;

	   $s = IO::Select->new();


	   @ready = $s->can_read($timeout);

	   @ready = IO::Select->new(@handles)->read(0);

       The "IO::Select" package implements an object approach to the system "select" function
       call. It allows the user to see what IO handles, see IO::Handle, are ready for reading,
       writing or have an error condition pending.

       new ( [ HANDLES ] )
	   The constructor creates a new object and optionally initialises it with a set of han-

       add ( HANDLES )
	   Add the list of handles to the "IO::Select" object. It is these values that will be
	   returned when an event occurs. "IO::Select" keeps these values in a cache which is
	   indexed by the "fileno" of the handle, so if more than one handle with the same
	   "fileno" is specified then only the last one is cached.

	   Each handle can be an "IO::Handle" object, an integer or an array reference where the
	   first element is an "IO::Handle" or an integer.

       remove ( HANDLES )
	   Remove all the given handles from the object. This method also works by the "fileno"
	   of the handles. So the exact handles that were added need not be passed, just handles
	   that have an equivalent "fileno"

       exists ( HANDLE )
	   Returns a true value (actually the handle itself) if it is present.	Returns undef

	   Return an array of all registered handles.

       can_read ( [ TIMEOUT ] )
	   Return an array of handles that are ready for reading. "TIMEOUT" is the maximum amount
	   of time to wait before returning an empty list, in seconds, possibly fractional. If
	   "TIMEOUT" is not given and any handles are registered then the call will block.

       can_write ( [ TIMEOUT ] )
	   Same as "can_read" except check for handles that can be written to.

       has_exception ( [ TIMEOUT ] )
	   Same as "can_read" except check for handles that have an exception condition, for
	   example pending out-of-band data.

       count ()
	   Returns the number of handles that the object will check for when one of the "can_"
	   methods is called or the object is passed to the "select" static method.

	   Return the bit string suitable as argument to the core select() call.

       select ( READ, WRITE, ERROR [, TIMEOUT ] )
	   "select" is a static method, that is you call it with the package name like "new".
	   "READ", "WRITE" and "ERROR" are either "undef" or "IO::Select" objects. "TIMEOUT" is
	   optional and has the same effect as for the core select call.

	   The result will be an array of 3 elements, each a reference to an array which will
	   hold the handles that are ready for reading, writing and have error conditions respec-
	   tively. Upon error an empty array is returned.

       Here is a short example which shows how "IO::Select" could be used to write a server which
       communicates with several sockets while also listening for more connections on a listen

	   use IO::Select;
	   use IO::Socket;

	   $lsn = new IO::Socket::INET(Listen => 1, LocalPort => 8080);
	   $sel = new IO::Select( $lsn );

	   while(@ready = $sel->can_read) {
	       foreach $fh (@ready) {
		   if($fh == $lsn) {
		       # Create a new socket
		       $new = $lsn->accept;
		   else {
		       # Process socket

		       # Maybe we have finished with the socket

       Graham Barr. Currently maintained by the Perl Porters.  Please report all bugs to

       Copyright (c) 1997-8 Graham Barr <gbarr@pobox.com>. All rights reserved.  This program is
       free software; you can redistribute it and/or modify it under the same terms as Perl

perl v5.8.0				    2002-06-01				  IO::Select(3pm)
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