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null(n)                                                                                              null(n)



NAME
       null - Create and manipulate null channels

SYNOPSIS
       package require Tcl

       package require memchan

       null


DESCRIPTION
       The  command  described  here is only available in a not-yet released version of the package. Use the
       CVS to get the sources.

       null   creates a null channel which absorbs everything written into it. Reading from it is not possi-ble, possible,
              ble,  or  rather  will  always  return zero bytes. These channels are essentially Tcl-specific
              variants of the null device for unixoid operating systems (/dev/null). Transfering the  gener-ated generated
              ated channel between interpreters is possible but does not make much sense.

OPTIONS
       Memory channels created by null provide one additional option to set or query.

       -delay ?milliseconds?
              A  null  channel  is always writable and readable. This means that all fileevent-handlers will
              fire continuously.  To avoid starvation of other event sources the events raised by this chan-nel channel
              nel type have a configurable delay. This option is set in milliseconds and defaults to 5.

       A  null  channel  is always writable and never readable. This means that a writable fileevent-handler
       will fire continuously and a readable fileevent-handler never at all. The exception to the latter  is
       only  the destruction of the channel which will cause the delivery of an eof event to a readable han-dler. handler.
       dler.

SEE ALSO
       fifo, fifo2, memchan, random, zero

KEYWORDS
       channel, i/o, in-memory channel, null

COPYRIGHT
       Copyright (c) 1996-2003 Andreas Kupries <andreas_kupries@users.sourceforge.net>




Memory channels                                      2.2                                             null(n)