php class定义

<?php
class PersonWriter {

    function writeName( Person $p ) {
        print $p->getName().'\n';
    }

    function writeAge( Person $p ) {
        print $p->getAge().'\n';
    }
}

class Person {
    private $writer;

    function __construct( PersonWriter $writer ) {
        $this->writer = $writer;
    }

    function __call( $method, $args ) {
        if ( method_exists( $this->writer, $method ) ) {
            return $this->writer->$method( $this );
        }
    }

    function getName()  { 
        return 'Joe'; 
    }
    function getAge() { 
        return 44; 
    }
}

$person= new Person( new PersonWriter() );
$person->writeName();
$person->writeAge();
?>