php-doc-en/language/oop5/anonymous.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision$ -->

<sect1 xml:id="language.oop5.anonymous" xmlns="http://docbook.org/ns/docbook">
 <title>Anonymous classes</title>

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

 <informalexample>
  <programlisting role="php">
<![CDATA[
<?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;
    }
});
]]>
  </programlisting>
 </informalexample>

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

 <informalexample>
  <programlisting role="php">
<![CDATA[
<?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;
});
]]>
  </programlisting>
  &example.outputs;
  <screen>
<![CDATA[
object(class@anonymous)#1 (1) {
  ["Command line code0x104c5b612":"class@anonymous":private]=>
  int(10)
}
]]>
  </screen>
 </informalexample>

 <para>
  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:
 </para>

 <informalexample>
  <programlisting role="php">
<![CDATA[
<?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();
]]>
  </programlisting>
  &example.outputs;
  <screen>
<![CDATA[
6
]]>
  </screen>
 </informalexample>
</sect1>
 
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