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2null(n)                                                                null(n)
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NAME

7       null - Create and manipulate null channels
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SYNOPSIS

10       package require Tcl
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12       package require memchan
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14       null
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DESCRIPTION

18       The command described here is only available in a not-yet released ver‐
19       sion of the package. Use the CVS to get the sources.
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21       null   creates a null channel which absorbs everything written into it.
22              Reading  from  it  is not possible, or rather will always return
23              zero bytes. These channels are essentially Tcl-specific variants
24              of  the  null  device for unixoid operating systems (/dev/null).
25              Transfering the generated channel between interpreters is possi‐
26              ble but does not make much sense.
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OPTIONS

29       Memory channels created by null provide one additional option to set or
30       query.
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32       -delay ?milliseconds?
33              A null channel is always writable and readable. This means  that
34              all fileevent-handlers will fire continuously.  To avoid starva‐
35              tion of other event sources the events raised  by  this  channel
36              type  have a configurable delay. This option is set in millisec‐
37              onds and defaults to 5.
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39       A null channel is always writable and never readable. This means that a
40       writable  fileevent-handler  will  fire  continuously  and  a  readable
41       fileevent-handler never at all. The exception to the latter is only the
42       destruction  of  the  channel  which  will cause the delivery of an eof
43       event to a readable handler.
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SEE ALSO

46       memchan, fifo, fifo2, random, zero
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KEYWORDS

49       null, in-memory channel, channel, i/o
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52       Copyright (c) 1996-2003 Andreas Kupries <andreas_kupries@users.sourceforge.net>
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56Memory channels                       2.2                              null(n)
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