PHP中如何覆盖父对象的静态属性并让父对象访问新值？

Question

这就是我所拥有的：所有可以持久保存在数据库上的对象都扩展了 DatabaseObject 抽象类，该抽象类具有实际监视属性更改和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详细信息。我一般在基类中定义它们，然后假设我在实际的数据库对象中覆盖它们。

问题是：当父类中的代码实际执行时，它使用旧的父值而不是当前对象值。

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;
    }
}

这是上面扩展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);
    }

}

我在这里做错了什么？还有其他方法可以达到相同的结果吗？

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

您正在寻找后期静态绑定。

所以你需要使用：

static::$databaseTable

而不是

self::$databaseTable

这个功能从 PHP 5.3 开始可用。在 PHP 5.2 中模拟这一点非常困难，原因有两个： get_called_class 仅从 PHP 5.3 起才可用。因此，它也必须使用 debug_backtrace 进行模拟。第二个问题是，如果您有被调用的类，您仍然可能无法使用 $usedClass::$property 因为这也是 PHP 5.3 的功能。这里需要使用eval或者Reflection。所以我真的希望你有 PHP 5.3 ;)