NAME

       memchan - Create and manipulate memory channels

SYNOPSIS

       package require Tcl

       package require memchan

       memchan ?-initial-size len?

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DESCRIPTION

       This  manpage  documents  both the overall package and the command memchan. 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.

COMMAND

       memchan ?-initial-size len?
              creates a chunk-oriented in-memory channel and returns its handle. If an initial size is specified
              the system will pre-allocate 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 accommodate the
              data written into it.

              The channels created here can be transferred 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 allocated 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 continuously.

       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 conditions a readable fileevent-handler will fire continuously.

       Note  that  writing  to  such a channel usually occurs at the end, thus suppressing 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, memchan

COPYRIGHT

       Copyright (c) 1996-2003 Andreas Kupries <andreas_kupries@users.sourceforge.net>

Memory channels                                        2.2                                         memchan(3tcl)