null - Create and manipulate null channels
Contents
Copyright
Copyright (c) 1996-2003 Andreas Kupries <andreas_kupries@users.sourceforge.net>
Memory channels 2.2 null(3tcl)
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.
Keywords
channel, i/o, in-memory channel, null
Name
null - Create and manipulate null channels
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
Synopsis
package require Tcl
package require memchannull
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