memchan(n)memchan(n)______________________________________________________________________________NAMEmemchan - Create and manipulate memory channels
SYNOPSIS
package require Tcl
package require memchan
memchan ?-initial-size len?
_________________________________________________________________DESCRIPTION
This manpage documents both the overall package and the command mem‐
chan. The package itself provides a number of in-memory channels which
can utilized to
· capture stream-like information in a natural way instead of
using set and append to manipulate strings
· or to transfer data between interpreters, in the same thread or
not.
COMMANDmemchan ?-initial-size len?
creates a chunk-oriented in-memory channel and returns its han‐
dle. If an initial size is specified the system will pre-allo‐
cate len bytes of buffer space for the contents. This is no
restriction on the ultimate size of the channel, it will always
grow as much as is necessary to accomodate the data written into
it.
The channels created here can be transfered between interpreters
in the same thread and between threads, but only as a whole. It
is not possible to use them to create a bi- or unidirectional
connection between two interpreters.
Memory channels created by memchan provide two read-only options which
can be queried via the standard fconfigure command. These are
-length
The value of this option is the number of bytes currently stored
in the queried memory channel.
-allocated
The value of this option is the number of bytes currently allo‐
cated by the queried memory channel. This number is at least as
big as the value of -length.
As the channels generated by memchan 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 and
the seek location is not and the end of the channel. Under these condi‐
tions a readable fileevent-handler will fire continuously.
Note that writing to such a channel usually occurs at the end, thus
supressing readable events. This also means that users have to take
care to seek the channel to a location before the end before trying to
read data back.
SEE ALSO
fifo, fifo2, null, random, zero
KEYWORDS
channel, chunk, i/o, in-memory channel, memchanCOPYRIGHT
Copyright (c) 1996-2003 Andreas Kupries <andreas_kupries@users.sourceforge.net>
Memory channels 2.2 memchan(n)
