paamayim nekudotayim documentation.

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Curt Zirzow 2004-07-17 04:51:27 +00:00
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<?xml version="1.0" encoding="iso-8859-1"?>
<!-- $Revision: 1.1 $ -->
<!-- $Revision: 1.2 $ -->
<sect1 id="language.oop5.paamayim-nekudotayim">
<title>::</title>
<para>
.
The Paamayim Nekudotayim, or in simpler terms, the double colon.
This token provides a way to access <link
linkend="language.oop5.static">static</link>, <link
linkend="language.oop5.constants">constant</link> or overridden members
or methods of a class.
</para>
<para>
When referencing these items from outside the class definition, you use
name of the class.
</para>
<example>
<title>:: from outside class definition</title>
<programlisting role="php">
<![CDATA[
<?php
class MyClass {
const CONST_VALUE = 'A constant value';
}
echo MyClass::CONST_VALUE;
?>
]]>
</programlisting>
</example>
<para>
Two special keywords <varname>self</varname> and <varname>parent</varname>
are used to access members or methods from inside the class definition.
</para>
<example>
<title>:: from inside the class definition</title>
<programlisting role="php">
<![CDATA[
<?php
class OtherClass extends MyClass {
public static $my_static = 'static var';
public static function doubleColon() {
echo parent::CONST_VALUE . "\n";
echo self::$my_static . "\n";
}
}
OtherClass::doubleColon();
?>
]]>
</programlisting>
</example>
<para>
When an extending class overrides the parents definition of a method,
php will not call the parent's method. It is up to the extending class
to call the parent method or not, this also applies to <link
linkend="language.oop5.decon">Constructors and Destructors</link>, <link
linkend="language.oop5.overloading">Overloading</link> and <link
linkend="language.oop5.magic">Magic</link> method defintions as well.
</para>
<example>
<title>Calling a parent's method</title>
<programlisting role="php">
<![CDATA[
<?php
class MyClass {
protected function myFunc() {
echo "MyClass::myFunc()\n";
}
}
class OtherClass extends MyClass {
/* Override parent's definition */
public function myFunc() {
/* But still call the parent function */
parent::myFunc();
echo "OtherClass::myFunc()\n";
}
}
$class = new OtherClass();
$class->myFunc();
?>
]]>
</programlisting>
</example>
</sect1>
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vim: et tw=78 syn=sgml
vi: ts=1 sw=1
-->