DragonFly On-Line Manual Pages

null(n)                                                                null(n)

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NAME
       null - Create and manipulate null channels

SYNOPSIS
       package require Tcl

       package require memchan

       null

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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 possible, or rather will always return
              zero bytes. These channels are essentially Tcl-specific variants
              of the null device for unixoid operating systems (/dev/null).
              Transferring the generated 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
              channel 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 handler.

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)