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Anonymous classes

Support for anonymous classes was added in PHP 7. Anonymous classes are useful when simple, one-off objects need to be created.

<?php

// Pre PHP 7 code
class  Logger
{
    public function 
log ( $msg )
    {
        echo 
$msg ;
    }
}

$util -> setLogger (new  Logger ());

// PHP 7+ code
$util -> setLogger (new class {
    public function 
log ( $msg )
    {
        echo 
$msg ;
    }
});

They can pass arguments through to their constructors, extend other classes, implement interfaces, and use traits just like a normal class can:

<?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 ;
});

以上例程会输出:

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 or protected 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 ();

以上例程会输出:

6