Final Keyword
Guide
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The final keyword prevents child classes from overriding a method, property, or constant by prefixing the definition with final. If the class itself is being defined final then it cannot be extended.
The final keyword prevents child classes from overriding a method, property, or constant by prefixing the definition with final. If the class itself is being defined final then it cannot be extended.
Final methods example
php
<?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()
?> Final class example
php
<?php
final class BaseClass {
public function test() {
echo "BaseClass::test() called\n";
}
// As the class is already final, the final keyword is redundant
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)
?> Final property example as of PHP 8.4.0
php
<?php
class BaseClass {
final protected string $test;
}
class ChildClass extends BaseClass {
public string $test;
}
// Results in Fatal error: Cannot override final property BaseClass::$test
?>Final constants example as of PHP 8.1.0
php
<?php
class Foo
{
final public const X = "foo";
}
class Bar extends Foo
{
public const X = "bar";
}
// Fatal error: Bar::X cannot override final constant Foo::X
?>Note
As of PHP 8.0.0, private methods may not be declared final except for the constructor.
Note
A property that is declared private(set) is implicitly final.