無名クラス

PHP 7 で、無名クラスをサポートするようになりました。 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

// PHP 7 より前のバージョンのコード
class Logger
{
    public function 
log($msg)
    {
        echo 
$msg;
    }
}

$util->setLogger(new Logger());

// PHP 7 以降のコード
$util->setLogger(new class {
    public function 
log($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 なメソッドそして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

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User Contributed Notes 6 notes

up
3
ytubeshareit at gmail dot com
7 months 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...
<?php

function 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 name
echo $another::$str;    //outputs foo
?>

The above is functionally the same as doing this....
<?php
class I_named_this_one{
    public static
$str="foo";
}
function
return_not_anon(){
    return
'I_named_this_one';
}
$clzz=return_not_anon();//get class name
echo $clzz::$str;
?>
up
19
Anonymous
1 year 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
1
j.m \ jamesweb \ ca
2 months 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
0
piotr at maslosoft dot com
7 months 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
solobot
1 month ago
eval() is workaround for generating multiple anonymous classes with static properties in loop
<?php
public function generateClassMap()
    {
        foreach (
$this->classMap as $tableName => $class)
        {
           
$c = null;
            eval(
'$c = new class extends \common\MyStaticClass {
                public static $tableName;
                public static function tableName()
                {
                    return static::$tableName;
                }
            };'
);
           
$c::$tableName = $this->replicationPrefix.$tableName;
           
$this->classMap[$tableName] = $c;

        }
    }
?>
thus every class will have its own $tableName instead of common ancestor.
up
-10
primipilus13 at gmail dot com
1 year ago
<?php

// using constructor and extends in anonymous class 

class A
{
    private
$name;   

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

    public function
getName()
    {
        return
$this->name;
    }
}

$b = new class('anonymous') extends A
{
    public function
getName()
    {
        return
parent::getName() . ' class';
    }
};

echo
$b->getName(), PHP_EOL;

// result: anonimous class
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