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.TH IO::Select 3 "2001-09-21" "perl v5.8.8" "Perl Programmers Reference Guide"
IO::Select \- OO interface to the select system call
\& $s = IO::Select->new();
\& $s->add($some_handle);
\& @ready = $s->can_read($timeout);
\& @ready = IO::Select->new(@handles)->can_read(0);
The \f(CW\*(C`IO::Select\*(C'\fR package implements an object approach to the system \f(CW\*(C`select\*(C'\fR
function call. It allows the user to see what \s-1IO\s0 handles, see IO::Handle,
are ready for reading, writing or have an exception pending.
.IP "new ( [ \s-1HANDLES\s0 ] )" 4
.IX Item "new ( [ HANDLES ] )"
The constructor creates a new object and optionally initialises it with a set
.IP "add ( \s-1HANDLES\s0 )" 4
.IX Item "add ( HANDLES )"
Add the list of handles to the \f(CW\*(C`IO::Select\*(C'\fR object. It is these values that
will be returned when an event occurs. \f(CW\*(C`IO::Select\*(C'\fR keeps these values in a
cache which is indexed by the \f(CW\*(C`fileno\*(C'\fR of the handle, so if more than one
handle with the same \f(CW\*(C`fileno\*(C'\fR is specified then only the last one is cached.
Each handle can be an \f(CW\*(C`IO::Handle\*(C'\fR object, an integer or an array
reference where the first element is an \f(CW\*(C`IO::Handle\*(C'\fR or an integer.
.IP "remove ( \s-1HANDLES\s0 )" 4
.IX Item "remove ( HANDLES )"
Remove all the given handles from the object. This method also works
by the \f(CW\*(C`fileno\*(C'\fR of the handles. So the exact handles that were added
need not be passed, just handles that have an equivalent \f(CW\*(C`fileno\*(C'\fR
.IP "exists ( \s-1HANDLE\s0 )" 4
.IX Item "exists ( HANDLE )"
Returns a true value (actually the handle itself) if it is present.
Return an array of all registered handles.
.IP "can_read ( [ \s-1TIMEOUT\s0 ] )" 4
.IX Item "can_read ( [ TIMEOUT ] )"
Return an array of handles that are ready for reading. \f(CW\*(C`TIMEOUT\*(C'\fR is
the maximum amount of time to wait before returning an empty list, in
seconds, possibly fractional. If \f(CW\*(C`TIMEOUT\*(C'\fR is not given and any
handles are registered then the call will block.
.IP "can_write ( [ \s-1TIMEOUT\s0 ] )" 4
.IX Item "can_write ( [ TIMEOUT ] )"
Same as \f(CW\*(C`can_read\*(C'\fR except check for handles that can be written to.
.IP "has_exception ( [ \s-1TIMEOUT\s0 ] )" 4
.IX Item "has_exception ( [ TIMEOUT ] )"
Same as \f(CW\*(C`can_read\*(C'\fR except check for handles that have an exception
condition, for example pending out-of-band data.
Returns the number of handles that the object will check for when
one of the \f(CW\*(C`can_\*(C'\fR methods is called or the object is passed to
the \f(CW\*(C`select\*(C'\fR static method.
Return the bit string suitable as argument to the core \fIselect()\fR call.
.IP "select ( \s-1READ\s0, \s-1WRITE\s0, \s-1EXCEPTION\s0 [, \s-1TIMEOUT\s0 ] )" 4
.IX Item "select ( READ, WRITE, EXCEPTION [, TIMEOUT ] )"
\&\f(CW\*(C`select\*(C'\fR is a static method, that is you call it with the package name
like \f(CW\*(C`new\*(C'\fR. \f(CW\*(C`READ\*(C'\fR, \f(CW\*(C`WRITE\*(C'\fR and \f(CW\*(C`EXCEPTION\*(C'\fR are either \f(CW\*(C`undef\*(C'\fR or
\&\f(CW\*(C`IO::Select\*(C'\fR objects. \f(CW\*(C`TIMEOUT\*(C'\fR 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
exceptions respectively. Upon error an empty list is returned.
Here is a short example which shows how \f(CW\*(C`IO::Select\*(C'\fR could be used
to write a server which communicates with several sockets while also
listening for more connections on a listen socket
\& $lsn = new IO::Socket::INET(Listen => 1, LocalPort => 8080);
\& $sel = new IO::Select( $lsn );
\& while(@ready = $sel->can_read) {
\& foreach $fh (@ready) {
\& # Maybe we have finished with the socket
Graham Barr. Currently maintained by the Perl Porters. Please report all
bugs to <perl5\-porters@perl.org>.
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 itself.
projects / OpenSPARC-T2-SAM / blob