PHP: Anonymous classes - Manual


    
     
      <?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
     
     
      ;
      

      });

The above example will output:

object(class@anonymous)#1 (1) { ["Command line code0x104c5b612":"class@anonymous":private]=> int(10) Nesting an anonymous class within another class does not give it access to any private or protected methods or properties of that outer class. In order to use the outer class' protected properties or methods, the anonymous class can extend the outer class. To use the private properties of the outer class in the anonymous class, they must be passed through its constructor:


    
     
      <?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
     
     
      ();

The above example will output:


    
     
      <?php
      

     
     
      function
     
     
      anonymous_class
     
     
      ()
      

      {
      

      return new class {};
      

      }
      

      

      if (
     
     
      get_class
     
     
      (
     
     
      anonymous_class
     
     
      ()) ===
     
     
      get_class
     
     
      (
     
     
      anonymous_class
     
     
      ())) {
      

      echo
     
     
      'same class'
     
     
      ;
      

      } else {
      

      echo
     
     
      'different class'
     
     
      ;
      

      }

The above example will output:

same class Note that anonymous classes are assigned a name by the engine, as demonstrated in the following example. This name has to be regarded an implementation detail, which should not be relied upon.


    
     
      <?php
      

     
     
      echo
     
     
      get_class
     
     
      (new class {});

The above example will output something similar to:

class@anonymous/in/oNi1A0x7f8636ad2021 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" ; 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 ;
?> I wanted to share my findings on static properties of anonymous classes.

So, given an anonymous class' object generating function like this:

<?php
function 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
?> /* 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 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. 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 ( '!' );
?> 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). 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. <?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