Static Keyword

Static Keyword

Tip: > This page describes the use of the keyword to define static methods and properties. can also be used to ,

and for
.
Please refer to those pages for information on those meanings of
.

static``staticdefine static variablesdefine static anonymous functionslate static bindingsstatic

Declaring class properties or methods as static makes them accessible without needing an instantiation of the class. These can also be accessed statically within an instantiated class object.

Static methods

Because static methods are callable without an instance of
the object created, the pseudo-variable  is
not available inside methods declared as static.

$this

Waarschuwing: > Calling non-static methods statically throws an . Error

 Prior to PHP 8.0.0, calling non-static methods statically was deprecated, and
 generated an  warning.
`E_DEPRECATED`

Voorbeeld: Static method example

<?php
class Foo {
    public static function aStaticMethod() {
        // ...
    }
}

Foo::aStaticMethod();
$classname = 'Foo';
$classname::aStaticMethod();
?>

Static properties

Static properties are accessed using the

() and cannot be accessed through the object operator
().

Scope Resolution Operator::``->

It's possible to reference the class using a variable.
The variable's value cannot be a keyword (e.g. ,
 and ).

self``parent``static

Voorbeeld: Static property example

<?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";

print Bar::$my_static . "\n";
$bar = new Bar();
print $bar->fooStatic() . "\n";
?>

foo
foo

Notice: Accessing static property Foo::$my_static as non static in /in/V0Rvv on line 23

Warning: Undefined property: Foo::$my_static in /in/V0Rvv on line 23

foo
foo
foo
foo