NAME¶
fifo2 - Create and manipulate pipe fifo channels
SYNOPSIS¶
package require
Tcl
package require
memchan
fifo2
DESCRIPTION¶
The command described here is only available in a not-yet released version 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 accommodate 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 transferred between interpreters in the
same thread and between threads. As both channels in the pair can be
transferred 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
available for reading from the channel.
- -wlength
- The value of this option is the number of bytes currently
written 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
continuously.
The channels are also readable if they contain more than zero bytes. Under this
conditions a readable
fileevent-handler will fire continuously.
SEE ALSO¶
fifo, memchan, null
KEYWORDS¶
channel, fifo, i/o, in-memory channel, memchan, stream
COPYRIGHT¶
Copyright (c) 1996-2003 Andreas Kupries <andreas_kupries@users.sourceforge.net>