Provided by: tcl-memchan_2.3+dfsg-1_amd64 bug


       null - Create and manipulate null channels


       package require Tcl

       package require memchan




       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.


       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.


       fifo, fifo2, memchan, random, zero


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


       Copyright (c) 1996-2003 Andreas Kupries <>