something advanced in the code preventing me from adding properties to the object

<?php
class Address {
    private $number;
    private $street;
    //public $streetaddress='no need for methods';
    public $maybestreet= 'this is it';

    function __construct( $maybenumber, $maybestreet=null ) {
        if ( is_null( $this->maybestreet ) ) {
            $this->streetaddress = $maybenumber;
        } else {
            $this->number = $maybenumber;
            $this->street = $maybestreet;
        }
    }

    function __set( $property, $value ) {
        if ( $property === "streetaddress" ) {
            if ( preg_match( "/^(\d+.*?)[\s,]+(.+)$/", $value, $matches ) ) {
                $this->number = $matches[1]; 
                $this->street = $matches[2]; 
            } else {
                throw new Exception("unable to parse street address: '{$value}'");
            }
        }    
    }

    function __get( $property ) {
        if ( $property === "streetaddress" ) {
            return $this->number." ".$this->street;
        }
    }
}

$address = new Address( "441b Bakers Street" );
print_r( $address );

print "street address: {$address->streetaddress}\n";
$address = new Address( 15, "Albert Mews" );
print "street address: {$address->streetaddress}\n";
$address->streetaddress = "34, West 24th Avenue";
print "street address: {$address->streetaddress}\n";
$address->numbersAndLetters='31 red rd';
$address->streetaddress = "failme";

?>

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