New self vs. new static
will I get the same results?
Not really. I don't know of a workaround for PHP 5.2, though.
What is the difference between
new self
andnew static
?
self
refers to the same class in which the new
keyword is actually written.
static
, in PHP 5.3's late static bindings, refers to whatever class in the hierarchy you called the method on.
In the following example, B
inherits both methods from A
. The self
invocation is bound to A
because it's defined in A
's implementation of the first method, whereas static
is bound to the called class (also see get_called_class()
).
class A { public static function get_self() { return new self(); } public static function get_static() { return new static(); }}class B extends A {}echo get_class(B::get_self()); // Aecho get_class(B::get_static()); // Becho get_class(A::get_self()); // Aecho get_class(A::get_static()); // A
If the method of this code is not static, you can get a work-around in 5.2 by using get_class($this)
.
class A { public function create1() { $class = get_class($this); return new $class(); } public function create2() { return new static(); }}class B extends A {}$b = new B();var_dump(get_class($b->create1()), get_class($b->create2()));
The results:
string(1) "B"string(1) "B"
In addition to others' answers :
static:: will be computed using runtime information.
That means you can't use static::
in a class property because properties values :
Must be able to be evaluated at compile time and must not depend on run-time information.
class Foo { public $name = static::class;}$Foo = new Foo;echo $Foo->name; // Fatal error
Using self::
class Foo { public $name = self::class;}$Foo = new Foo;echo $Foo->name; // Foo
Please note that the Fatal error comment in the code i made doesn't indicate where the error happened, the error happened earlier before the object was instantiated as @Grapestain mentioned in the comments