README for IO::Multiplex

IO::Multiplex is designed to take the effort out of managing
multiple file handles.  It is essentially a really fancy front end to
the C<select> system call.  In addition to maintaining the C<select>
loop, it buffers all input and output to/from the file handles.  It
can also accept incoming connections on one or more listen sockets.

It is object oriented in design, and will notify you of significant events
by calling methods on an object that you supply.  If you are not using
objects, you can simply supply __PACKAGE__ instead of an object reference.

You may have one callback object registered for each file handle, or
one global one.  Possibly both -- the per-file handle callback object
will be used instead of the global one.

Each file handle may also have a timer associated with it.  A callback
function is called when the timer expires.

Here's an example which implements the beginnings of a multiuser game:

    use IO::Socket;
    use IO::Multiplex;
    use Tie::RefHash;
    my $mux  = new IO::Multiplex;

    # Create a listening socket
    my $sock = new IO::Socket::INET(Proto     => 'tcp',
                                    LocalPort => shift || 2300,
                                    Listen    => 4)
        or die "socket: $@";

    # We use the listen method instead of the add method.
    # mux_connection is called when a new connection is accepted.
    sub mux_connection {
        my $package = shift;
        my $mux     = shift;
        my $fh      = shift;

        # Construct a new player object
        Player->new($mux, $fh);

    package Player;

    my %players = ();

    sub new {
        my $package = shift;
        my $self    = bless { mux  => shift,
                              fh   => shift } => $package;

        # Register the new player object as the callback specifically for
        # this file handle.
        $mux->set_callback_object($self, $self->{fh});
        print $self->{fh}
            "Greetings, Professor.  Would you like to play a game?\n";

        # Register this player object in the main list of players
        $players{$self} = $self;
        $mux->set_timeout($self->{fh}, 1);

    sub players { return values %players; }

    sub mux_input {
        my $self = shift;
        shift; shift;         # These two args are boring
        my $input = shift;    # Scalar reference to the input

        # Process each line in the input, leaving partial lines
        # in the input buffer
        while ($$input =~ s/^(.*?\n)//) {

    sub mux_close {
       my $self = shift;

       # Player disconnected;
       # [Notify other players or something...]
       delete $players{$self};
    # This gets called every second to update player info, etc...
    sub mux_timeout {
        my $self = shift;
        my $mux  = shift;
        $mux->set_timeout($self->{fh}, 1);