NAME¶
null - Create and manipulate null channels
SYNOPSIS¶
package require
Tcl
package require
memchan
null
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>
