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# tcl::chan::fifo2(n) 1 tcllib "Reflected/virtual channel support"

## Name

tcl::chan::fifo2 - In-memory interconnected fifo channels

## Synopsis

- package require Tcl 8.5
- package require TclOO
- package require tcl::chan::events ?1?
- package require tcl::chan::halfpipe ?1?
- package require tcl::chan::fifo2 ?1?

- ::tcl::chan::fifo2

## Description

The tcl::chan::fifo2 package provides a command creating pairs of channels which live purely in memory and are connected to each other in a fifo manner. What is written to one half of the pair can be read from the other half, in the same order. One particular application for this is communication between threads, with one half of the pair moved to the thread to talk to. This is equivalent to the fifo2 channels provided by the package Memchan, except that this is written in pure Tcl, not C. On the other hand, Memchan is usable with Tcl 8.4 and before, whereas this package requires Tcl 8.5 or higher, and TclOO.

The internal TclOO class implementing the channel handler is a sub-class of the tcl::chan::events framework.

## API

::tcl::chan::fifo2

  This command creates a new connected pair of fifo channels and returns their handles, as a list containing two elements.

## Bugs, Ideas, Feedback

This document, and the package it describes, will undoubtedly contain bugs and other problems. Please report such in the category virtchannel of the Tcllib Trackers. Please also report any ideas for enhancements you may have for either package and/or documentation.

When proposing code changes, please provide unified diffs, i.e the output of diff -u.

Note further that attachments are strongly preferred over inlined patches. Attachments can be made by going to the Edit form of the ticket immediately after its creation, and then using the left-most button in the secondary navigation bar.

## Keywords

connected fifos, fifo, in-memory channel, inter-thread communication, reflected channel, tip 219, virtual channel

## Category

Channels

## Copyright

Copyright © 2009 Andreas Kupries <andreas_kupries@users.sourceforge.net>