# Programming Ruby ### The Pragmatic Programmer's Guide
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class ThreadGroup |
Parent: | Object
Version: | 1.6

### Index:

new add list

`ThreadGroup` provides a means of keeping track of a number of threads as a group. A `Thread` can belong to only one `ThreadGroup` at a time; adding a thread to a new group will remove it from any previous group.

Newly created threads belong to the same group as the thread from which they were created.

constants

`Default` |  | Default thread group.

class methods
new | ThreadGroup.new -> thgrp
|  | Returns a newly created `ThreadGroup`. The group is initially empty.

instance methods
add | thgrp.add( aThread ) -> thgrp
|  | Adds the given thread to this group, removing it from any other group to which it may have previously belonged.
    puts "Initial group is #{ThreadGroup::Default.list}"
    tg = ThreadGroup.new
    t1 = Thread.new { sleep 10 }
    t2 = Thread.new { sleep 10 }
    puts "t1 is #{t1}"
    puts "t2 is #{t2}"
    tg.add( t1 )
    puts "Initial group now #{ThreadGroup::Default.list}"
    puts "tg group now #{tg.list}"
produces:
    Initial group is #<Thread:0x401be5c8>
    t1 is #<Thread:0x401b5428>
    t2 is #<Thread:0x401b53d8>
    Initial group now #<Thread:0x401b53d8>#<Thread:0x401be5c8>
    tg group now #<Thread:0x401b5428>
list | thgrp.list -> anArray
|  | Returns an array of all existing `Thread` objects that belong to this group.
`ThreadGroup::Default.list` | » | `[#<Thread:0x401be5c8 run>]`

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Extracted from the book "Programming Ruby - The Pragmatic Programmer's Guide"
Copyright © 2001 by Addison Wesley Longman, Inc. This material may be distributed only subject to the terms and conditions set forth in the Open Publication License, v1.0 or later (the latest version is presently available at http://www.opencontent.org/openpub/)).

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