fifo2(n) fifo2(n) ______________________________________________________________________________
NAME
fifo2 - Create and manipulate pipe fifo channels
SYNOPSIS
package require Tcl
package require memchan
fifo2
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DESCRIPTION
The command described here is only available in a not-yet released ver-
sion of the package. Use the CVS to get the sources.
fifo2 creates two stream-oriented in-memory channels and returns their
handles as a two-element list. There is no restriction on the
ultimate size of the channels, they will always grow as much as
is necessary to accomodate the data written into them.
In contrast to the channels generated by fifo a pair of channels
created here is connected internally in such a way that data
written into one channel can be read from the other. All data
written into them is read in the same order. This also means
that the two channels of the pair are not seekable.
The channels created here can be transfered between interpreters
in the same thread and between threads. As both channels in the
pair can be transfered independently they can be used to create
a bidirectional connection between two interpreters.
Memory channels created by fifo2 provide two read-only options which
can be queried via the standard fconfigure command. These are
-rlength
The value of this option is the number of bytes currently avail-
able for reading from the channel.
-wlength
The value of this option is the number of bytes currently writ-
ten into the channel.
Note that the two lengths are switched for the channels of a pair. In
other words, the number of bytes written for one of the channels is the
number of bytes readable from the other end.
As the channels generated by fifo2 grow as necessary they are always
writable. This means that a writable fileevent-handler will fire con-
tinuously.
The channels are also readable if they contain more than zero bytes.
Under this conditions a readable fileevent-handler will fire continu-
ously.
SEE ALSO
fifo(n), memchan(n), null(n)
KEYWORDS
channel, fifo, i/o, in-memory channel, memchan, stream
COPYRIGHT
Copyright (c) 1996-2003 Andreas Kupries <andreas_kupries@users.sourceforge.net>
Memory channels 2.2 fifo2(n)
Mac OS X 10.8 - Generated Thu Sep 6 10:43:10 CDT 2012