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

## Name

tcl::chan::cat - Concatenation channel

## Synopsis

- package require Tcl 8.5
- package require TclOO
- package require tcl::chan::core ?1?
- package require tcl::chan::cat ?1?

- ::tcl::chan::cat chan...

## Description

The tcl::chan::cat package provides a command creating concatenation channels. These are non-seekable channels owning a list of subordinate channels whose contents they return in order, until all are exhausted. In this manner the channel is the concatentation of the contents of all the sub-ordinate channels.

Note that the created channels take ownership of the channels they were constructed with. Whenever they have exhausted one of their channel it will be closed. Similarly, closing the cat channel will close all the sub-ordinates it still has.

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

Event handling is delegated to the currently active sub-channel.

## API

::tcl::chan::cat chan...

  This command creates the concatenation channel using all the provided channels, and returns its handle.

## 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

concatenation channel, reflected channel, tip 219, virtual channel

## Category

Channels

## Copyright

Copyright © 2011 Andreas Kupries <andreas_kupries@users.sourceforge.net>