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
|
<?xml version="1.0" encoding="iso-8859-1"?>
<!-- $Revision: 1.7 $ -->
<sect1 id="language.oop5.constants">
<title>Class Constants</title>
<para>
It is possible to define constant values on a per-class basis remaining the
same and unchangeable. Constants differ from normal variables in that you
don't use the <varname>$</varname> symbol to declare or use them. Like
<link linkend="language.oop5.static">static</link> members, constant values
cannot be accessed from an instance of the object (using
<literal>$object::constant</literal>).
</para>
<para>
The value must be a constant expression, not (for example) a variable, a
class member, result of a mathematical operation or a function call.
</para>
<example>
<title>Defining and using a constant</title>
<programlisting role="php">
<![CDATA[
<?php
class MyClass
{
const constant = 'constant value';
function showConstant() {
echo self::constant . "\n";
}
}
echo MyClass::constant . "\n";
$class = new MyClass();
$class->showConstant();
// echo $class::constant; is not allowed
?>
]]>
</programlisting>
</example>
</sect1>
<!-- Keep this comment at the end of the file
Local variables:
mode: sgml
sgml-omittag:t
sgml-shorttag:t
sgml-minimize-attributes:nil
sgml-always-quote-attributes:t
sgml-indent-step:1
sgml-indent-data:t
indent-tabs-mode:nil
sgml-parent-document:nil
sgml-default-dtd-file:"../../manual.ced"
sgml-exposed-tags:nil
sgml-local-catalogs:nil
sgml-local-ecat-files:nil
End:
vim600: syn=xml fen fdm=syntax fdl=2 si
vim: et tw=78 syn=sgml
vi: ts=1 sw=1
-->
|
