無名クラス

無名クラスは、その場限りの使い捨てのオブジェクトが必要になった場合に便利です。

<?php

// 明示的にクラスを宣言して使う
class Logger
{
public function
log($msg)
{
echo
$msg;
}
}

$util->setLogger(new Logger());

// 無名クラスを使う
$util->setLogger(new class {
public function
log($msg)
{
echo
$msg;
}
});

コンストラクタを使って引数を渡したり、他のクラスを継承したり、 インターフェイスを実装したり、トレイトを使ったりといった、 普通のクラスと同じようなことが可能です。

<?php

class SomeClass {}
interface
SomeInterface {}
trait
SomeTrait {}

var_dump(new class(10) extends SomeClass implements SomeInterface {
private
$num;

public function
__construct($num)
{
$this->num = $num;
}

use
SomeTrait;
});

上の例の出力は以下となります。

object(class@anonymous)#1 (1) {
  ["Command line code0x104c5b612":"class@anonymous":private]=>
  int(10)
}

無名クラスを別のクラス内で作っても、外側のクラスの private や protected なメソッド、 およびプロパティにはアクセスできません。 外側のクラスの protected プロパティやメソッドにアクセスするには、 無名クラスに外側のクラスを継承させます。 外側のクラスの private プロパティを無名クラスで使うには、 コンストラクタでそれを渡す必要があります。

<?php

class Outer
{
private
$prop = 1;
protected
$prop2 = 2;

protected function
func1()
{
return
3;
}

public function
func2()
{
return new class(
$this->prop) extends Outer {
private
$prop3;

public function
__construct($prop)
{
$this->prop3 = $prop;
}

public function
func3()
{
return
$this->prop2 + $this->prop3 + $this->func1();
}
};
}
}

echo (new
Outer)->func2()->func3();

上の例の出力は以下となります。

6

同じ無名クラス宣言から作ったすべてのオブジェクトは、その同じクラスのインスタンスとなります。

<?php
function anonymous_class()
{
return new class {};
}

if (
get_class(anonymous_class()) === get_class(anonymous_class())) {
echo
'同じクラス';
} else {
echo
'違うクラス';
}

上の例の出力は以下となります。

同じクラス

注意:

無名クラスには内部的な名前が付けられていることに注意しましょう。これは次の例で確認できます。 ただこれは細部の実装上の話なので、この名前に依存するコードを書いてはいけません。

<?php
echo get_class(new class {});

上の例の出力は、 たとえば以下のようになります。

class@anonymous/in/oNi1A0x7f8636ad2021

add a note

User Contributed Notes 8 notes

up
50
Anonymous
9 years ago
Below three examples describe anonymous class with very simple and basic but quite understandable example<?php// First way - anonymous class assigned directly to variable$ano_class_obj = new class{    public $prop1 = 'hello';    public $prop2 = 754;    const SETT = 'some config';    public function getValue()    {        // do some operation        return 'some returned value';    }    public function getValueWithArgu($str)    {        // do some operation        return 'returned value is '.$str;    }};echo "\n";var_dump($ano_class_obj);echo "\n";echo $ano_class_obj->prop1;echo "\n";echo $ano_class_obj->prop2;echo "\n";echo $ano_class_obj::SETT;echo "\n";echo $ano_class_obj->getValue();echo "\n";echo $ano_class_obj->getValueWithArgu('OOP');echo "\n";echo "\n";// Second way - anonymous class assigned to variable via defined function$ano_class_obj_with_func = ano_func();function ano_func(){    return new class {        public $prop1 = 'hello';        public $prop2 = 754;        const SETT = 'some config';        public function getValue()        {            // do some operation            return 'some returned value';        }        public function getValueWithArgu($str)        {            // do some operation            return 'returned value is '.$str;        }    };}echo "\n";var_dump($ano_class_obj_with_func);echo "\n";echo $ano_class_obj_with_func->prop1;echo "\n";echo $ano_class_obj_with_func->prop2;echo "\n";echo $ano_class_obj_with_func::SETT;echo "\n";echo $ano_class_obj_with_func->getValue();echo "\n";echo $ano_class_obj_with_func->getValueWithArgu('OOP');echo "\n";echo "\n";// Third way - passing argument to anonymous class via constructors$arg = 1; // we got it by some operation$config = [2, false]; // we got it by some operation$ano_class_obj_with_arg = ano_func_with_arg($arg, $config);function ano_func_with_arg($arg, $config){    return new class($arg, $config) {        public $prop1 = 'hello';        public $prop2 = 754;        public $prop3, $config;        const SETT = 'some config';        public function __construct($arg, $config)        {            $this->prop3 = $arg;            $this->config =$config;        }        public function getValue()        {            // do some operation            return 'some returned value';        }        public function getValueWithArgu($str)        {            // do some operation            return 'returned value is '.$str;        }    };}echo "\n";var_dump($ano_class_obj_with_arg);echo "\n";echo $ano_class_obj_with_arg->prop1;echo "\n";echo $ano_class_obj_with_arg->prop2;echo "\n";echo $ano_class_obj_with_arg::SETT;echo "\n";echo $ano_class_obj_with_arg->getValue();echo "\n";echo $ano_class_obj_with_arg->getValueWithArgu('OOP');echo "\n";echo "\n";
up
24
ytubeshareit at gmail dot com
8 years ago
Anonymous classes are syntax sugar that may appear deceiving to some.The 'anonymous' class is still parsed into the global scope, where it is auto assigned a name, and every time the class is needed, that global class definition is used.  Example to illustrate....The anonymous class version...<?phpfunction return_anon(){    return new class{         public static $str="foo";      };}$test=return_anon();echo $test::$str; //ouputs foo//we can still access the 'anon' class directly in the global scope! $another=get_class($test); //get the auto assigned nameecho $another::$str;    //outputs foo?>The above is functionally the same as doing this....<?phpclass I_named_this_one{    public static $str="foo";}function return_not_anon(){    return 'I_named_this_one';}$clzz=return_not_anon();//get class nameecho $clzz::$str;?>
up
10
sebastian.wasser at gmail
6 years ago
I wanted to share my findings on static properties of anonymous classes.So, given an anonymous class' object generating function like this:<?phpfunction nc () {    return new class {        public static $prop = [];    };}?>Getting a new object and changing the static property:<?php$a = nc();$a::$prop[] = 'a';var_dump($a::$prop);// array(1) {//   [0] =>//   string(1) "a"// }?>Now getting another object and changing the static property will change the original one, meaning that the static property is truly static:<?php$b = nc();$b::$prop[] = 'b';var_dump($b::$prop); // Same as var_dump($a::$prop);// array(2) {//   [0] =>//   string(1) "a"//   [1] =>//   string(1) "b"// }assert($a::$prop === $b::$prop); // true?>
up
9
j.m \ jamesweb \ ca
7 years ago
/* I like the idea of OneShot classes.Thanks to that Anonymous bro\sist for precising   new class( $a, $b )¯¯¯¯¯¯¯¯¯If you are looking for "Delayed OneShot Anonymous Classes" for any reason (like the reason: loading files in a readable manner while not using autoload), it would probably look something like this; */$u = function()use(&$u){    $u = new class{private $name = 'Utils';};};$w = function(&$rewrite)use(&$w){    $w = null;    $rewrite = new class{private $name = 'DataUtils';};};// Usage;var_dump(    array(        'Delayed',        '( Self Destructive )',        'Anonymous Class Creation',        array(            'Before ( $u )' => $u,            'Running ( $u() )' => $u(),            'After ( $u )' => $u,        ),        0,0,        0,0,        0,0,        'Delayed',        '( Overwriting && Self Destructive )',        'Anonymous Class Creation',        array(            'Before ( $w )' => $w,            'Running ( $w($u) )' => $w($u),            'After ( $w )' => $w,            'After ( $u )' => $u        )    ));// btw : oh shoot I failed a spam challenge
up
7
joey
6 years ago
The only way to type hint this would appear to be as object.If you need multiple instances of an anonymous class in a function you can use:$class = function(string $arg):object {    return new class($arg) {        public function __construct(string $arg) {            $this->ow = $arg;        }    };};Though for the sake of structure it's ill advised to do something like this outside of a single scope or that's used across multiple files. If you class is only used in one scope however then it's probably not a code mess problem.
up
3
razvan_bc at yahoo dot com
5 years ago
you can try these<?php $oracle=&$_['nice_php'];$_['nice_php']=(function(){    return new class{        public static function say($msg){            echo $msg;        }        public static function sp(){            echo self::say(' ');        }    };});/*$_['nice_php']()::say('Hello');$_['nice_php']()::sp();$_['nice_php']()::say('World');$_['nice_php']()::sp();$_['nice_php']()::say('!');//almost the same code bottom*/$oracle()::say('Hello');$oracle()::sp();$oracle()::say('World');$oracle()::sp();$oracle()::say('!');?>
up
1
piotr at maslosoft dot com
8 years ago
Please note that class name returned by `get_class` might contain null bytes, as is the case in my version of PHP (7.1.4). Name will change when class starting line or it's body is changed.Yes, name is implementation detail that should not be relied upon, but in some rare use cases it is required (annotating anonymous class).
up
1
ismaelj+php at hotmail dot com
11 months ago
Thanks to the new property hooks in PHP 8.4 (https://wiki.php.net/rfc/property-hooks) and anonymous functions, now we can create an inner class instantiated only on use:<?phpclass BaseClass {  public function __construct() { echo "base class\n"; }  public $childClass  { set {}  get {    if ($this->childClass === null ) {      $this->childClass = new class {        public function __construct() { echo "  child class\n"; }        public function say(string $s) : void { echo "     $s\n"; }      };    }    return $this->childClass;    }  }}$base = new BaseClass();$base->childClass->say('Hello');$base->childClass->say('World');/*Output:base class  child class     Hello     World*/?>The obvious downside is that you can't set a type to the child class, unless  you define an interface and the child class implements it or if the child class extends an existing class:<?phpclass ParentClass {  public function say(string $s) : void { echo "     $s\n"; }}class BaseClass {  public function __construct() { echo "base class\n"; }  public ParentClass $childClass { set {}  get {    if (!isset($this->childClass)) {      $this->childClass = new class extends ParentClass {        public function __construct() { echo "  child class\n"; }      };    }    return $this->childClass;    }  }}$base = new BaseClass();$base->childClass->say('Hello');$base->childClass->say('World');/*Output:base class  child class     Hello     World*/?>?>This can be also done with functions, but  with hooks to me looks more like in other languages that have this functionality natively.
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