1null(n)                                                                null(n)
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NAME

8       null - Create and manipulate null channels
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SYNOPSIS

11       package require Tcl
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13       package require memchan
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15       null
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DESCRIPTION

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

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

48       fifo, fifo2, memchan, random, zero
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KEYWORDS

51       channel, i/o, in-memory channel, null
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54       Copyright (c) 1996-2003 Andreas Kupries <andreas_kupries@users.sourceforge.net>
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59Memory channels                       2.2                              null(n)
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