Static Keyword

Examples:

Static method example

<?php
class Foo {
    public static function aStaticMethod() {
        // ...
    }
}
 
Foo::aStaticMethod();
$classname = 'Foo';
$classname::aStaticMethod(); // As of PHP 5.3.0
?>

Static property example

Static properties cannot be accessed through the object using the arrow operator ->.

Like any other PHP static variable, static properties may only be initialized using a literal or constant before PHP 5.6; expressions are not allowed. In PHP 5.6 and later, the same rules apply as const expressions: some limited expressions are possible, provided they can be evaluated at compile time.

As of PHP 5.3.0, it's possible to reference the class using a variable. The variable's value cannot be a keyword (e.g. self, parent and static).

<?php
class Foo
{
    public static $my_static = 'foo';
 
    public function staticValue() {
        return self::$my_static;
    }
}
 
class Bar extends Foo
{
    public function fooStatic() {
        return parent::$my_static;
    }
}
 
 
print Foo::$my_static . "\n";
 
$foo = new Foo();
print $foo->staticValue() . "\n";
print $foo->my_static . "\n";      // Undefined "Property" my_static 
 
print $foo::$my_static . "\n";
$classname = 'Foo';
print $classname::$my_static . "\n"; // As of PHP 5.3.0
 
print Bar::$my_static . "\n";
$bar = new Bar();
print $bar->fooStatic() . "\n";
?>

Links:

http://php.net/manual/en/language.oop5.static.php

doc_php

2025-01-10 15:47:30

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