Newer
Older
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
<?php
/*********************************************************************
class.signal.php
Simple interface for a publish and subscribe signal model
Jared Hancock <jared@osticket.com>
Copyright (c) 2006-2013 osTicket
http://www.osticket.com
Released under the GNU General Public License WITHOUT ANY WARRANTY.
See LICENSE.TXT for details.
vim: expandtab sw=4 ts=4 sts=4:
**********************************************************************/
/**
* Signals implement a simple publish/subscribe event model. To keep things
* simplistic between classes and to maintain compatible with PHP version 4,
* signals will not be explicitly defined or registered. Instead, signals
* are connected to callbacks via a string signal name.
*
* The system is proofed with a static inspection test which will ensure
* that for every given Signal::connect() function call, somewhere else in
* the codebase there exists a Signal::send() for the same named signal.
*/
class Signal {
/**
* Subscribe to a signal.
*
* Signal::connect('user.auth', 'function');
*
* The subscribed function should receive a two arguments and will have
* this signature:
*
* function callback($object, $data);
*
* Where the $object argument is the object originating the signal, and
* the $options is a hash-array of other information originating from-
* and pertaining to the signal.
*
* The value of the $data argument is not defined. It is signal
* specific. It should be a hash-array of data; however, no runtime
* checks are made to ensure such an interface.
*
* Optionally, if $object is a class and is passed into the ::connect()
* method, only instances of the named class or subclass will actually
* be connected to the callable function.
*/
/*static*/ function connect($signal, $callable, $object=null) {
global $_subscribers;
if (!isset($_subscribers[$signal])) $_subscribers[$signal] = array();
// XXX: Ensure $object if set is a class
if ($object && !is_string($object))
trigger_error("Invalid object: $object: Expected class");
$_subscribers[$signal][] = array($object, $callable);
}
/**
* Publish a signal.
*
* Signal::send('user.login', $this, array('username'=>'blah'));
*
* All subscribers to the signal will be called in the order they
* connect()ed to the signal. Subscribers do not have the opportunity to
* interrupt or discontinue delivery of the signal to other subscribers.
* The $object argument is required and should almost always be ($this).
* Its interpretation is the object originating or sending the signal.
* It could also be interpreted as the context of the signal.
*
* $data if sent should be a hash-array of data included with the signal
* event. There is otherwise no definition for what should or could be
* included in the $data array. The received data is received by
* reference and can be passed to the callable by reference if the
* callable is defined to receive it by reference. Therefore, it is
* possible to propogate changes in the signal handlers back to the
* originating context.
*/
/*static*/ function send($signal, $object, &$data=null) {
global $_subscribers;
if (!isset($_subscribers[$signal]))
return;
foreach ($_subscribers[$signal] as $sub) {
list($s, $callable) = $sub;
if ($s && !is_a($object, $s))
continue;
call_user_func($callable, $data);
}
}
}
$_subscribers = array();
?>