fifo2(n) fifo2(n) 







fifo2 - Create and manipulate pipe fifo channels








package require Tcl 


package require memchan 


fifo2












The command described here is only available in a not-yet released
    version of the package. Use the CVS to get the sources.



  

  
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



  

  
The value of this option is the number of bytes currently available for
      reading from the channel.

  

  
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.








fifo, memchan, null








channel, fifo, i/o, in-memory channel, memchan, stream








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








  

    2.2
    Memory channels