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<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision: 297028 $ -->
<sect1 xml:id="language.oop5.final" xmlns="http://docbook.org/ns/docbook">
<title>Final Keyword</title>
<para>
PHP 5 introduces the final keyword, which prevents child classes from
overriding a method by prefixing the definition with final. If the class
itself is being defined final then it cannot be extended.
</para>
<para>
<example>
<title>Final methods example</title>
<programlisting role="php">
<![CDATA[
<?php
class BaseClass {
public function test() {
echo "BaseClass::test() called\n";
}
final public function moreTesting() {
echo "BaseClass::moreTesting() called\n";
}
}
class ChildClass extends BaseClass {
public function moreTesting() {
echo "ChildClass::moreTesting() called\n";
}
}
// Results in Fatal error: Cannot override final method BaseClass::moreTesting()
?>
]]>
</programlisting>
</example>
</para>
<para>
<example>
<title>Final class example</title>
<programlisting role="php">
<![CDATA[
<?php
final class BaseClass {
public function test() {
echo "BaseClass::test() called\n";
}
// Here it doesn't matter if you specify the function as final or not
final public function moreTesting() {
echo "BaseClass::moreTesting() called\n";
}
}
class ChildClass extends BaseClass {
}
// Results in Fatal error: Class ChildClass may not inherit from final class (BaseClass)
?>
]]>
</programlisting>
</example>
</para>
<note>
<simpara>
Properties cannot be declared final, only classes and methods
may be declared as final.
</simpara>
</note>
</sect1>
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