如何覆盖父对象的静态属性,让父对象访问PHP中的新值？

Question

这就是我所拥有的:可以持久保存在数据库中的所有对象都扩展了DatabaseObject抽象类,该抽象类具有实际监视属性更改并运行数据库查询的所有逻辑代码.

我使用两个静态变量来定义特定于对象的细节.我一般在基类中定义它们,然后据说我在实际的数据库对象中覆盖它们.

问题是:当实际执行父类中的代码时,它使用旧的父值而不是当前的对象值.

这是基类的代码:

abstract class DatabaseObject {

    public $id;

    private static $databaseTable = NULL;
    private static $databaseFields = array();

    private $data = array();
    private $changedFields = array();

    public function IDatabaseObject($id) {
    $this->id = $id;
    $this->data = Database::GetSingle(self::$databaseTable, $id);

    Utils::copyToObject($this, $this->data, self::$databaseFields);
    }

    public static function Load($id) {
    return new self($userID);
    }

    public static function Create($data) {

    $id = Database::Insert(self::$databaseTable, $data);

    return new self($id);
    }

    public function Save() {
    $data = Utils::copyFromObject($this, $this->changedFields);

    Database::Update(self::$databaseTable, $data, $this->id);

    }

    public function __constructor() {
    // We do this to allow __get and __set to be called on public vars
    foreach(self::$databaseFields as $field) {
        unset($this->$field);
    }
    }

    public function __get($variableName) {
    return $this->$variableName;
    }

    public function __set($variableName, $variableValue) {
    // We only want to update what has been changed
    if(!in_array($variableName, $this->changedFields) && in_array($variableName, self::$databaseFields)) {
        array_push($this->changedFields, $variableName);
    }

    $this->$variableName = $variableValue;
    }
}

这里是扩展上面基类的对象之一的代码:

class Client extends DatabaseObject {

    public static $databaseTable = "clients";
    public static $databaseFields = array("name","contactName","primaryUserID","email","is_active","rg","cpf","cnpj","ie","addrType","addrName","addrNumber","addrComplement","addrPostalCode","addrNeighborhood","addrCity","addrState","addrCountry","phoneLandline","phoneFax","phoneMobile");

    public $name;
    public $contactName;

    public $primaryUserID;
    public $email;

    public $is_active;

    public $rg;
    public $cpf;
    public $cnpj;
    public $ie;

    public $addrType;
    public $addrName;
    public $addrNumber;
    public $addrComplement;
    public $addrPostalCode;
    public $addrNeighborhood;
    public $addrCity;
    public $addrState;
    public $addrCountry;

    public $phoneLandline;
    public $phoneFax;
    public $phoneMobile;

    public static function Load($id) {
 return new Client($id);
    }

}

我在这做错了什么？还有另一种方法可以达到相同的效果吗？

一个简短的附录:我在类主体中声明属性主要是为了让NetBeans的自动完成功能看到它.

Answer 1

您正在寻找Late Static Binding.

所以你需要使用:

static::$databaseTable

代替

self::$databaseTable

从PHP 5.3开始提供此功能.在PHP 5.2中模拟这个很难,因为有两个原因:get_called_class从PHP 5.3开始也是如此.因此,必须使用它进行模拟debug_backtrace.第二个问题是,如果你有被调用的类,你仍然可能不会使用,$calledClass::$property因为这也是一个PHP 5.3功能.在这里你需要使用eval或Reflection.所以我希望你有PHP 5.3;)