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限制getter和setter可访问属性

getter-setter visibility overloading class php

user1032531 · 技术社区 · 6 年前

如何使用php的魔力 __get() 和 __set() 方法和限制支持哪些属性?

我通常看到php的魔术方法用于重载下面两种方法,但都没有。

我知道我可以硬编码一些逻辑,但这样做并不能使类非常可扩展。

$obj1=new Entity1(new Foo, new Bar);
$obj1->propAccessible1='propAccessible1';           //Valid
var_dump($obj1->propAccessible1);                   //Valid
$obj1->privateObject1='privateObject1';             //Should not be allowed
var_dump($obj1->privateObject1);                    //Should not be allowed
$obj1->unsupportedProperty='unsupportedProperty';   //Correctly is not allowed
var_dump($obj1->unsupportedProperty);               //Correctly is not allowed

$obj2=new Entity2(new Foo, new Bar);
$obj2->propAccessible1='propAccessible1';           //Valid
var_dump($obj2->propAccessible1);                   //Valid
$obj2->privateObject1='privateObject1';             //Should not be allowed
var_dump($obj2->privateObject1);                    //Should not be allowed (will be if first set using setter)
$obj2->unsupportedProperty='unsupportedProperty';   //Should not be allowed
var_dump($obj2->unsupportedProperty);               //Should not be allowed

class Foo{}
class Bar{}

class Entity1
{
    private $privateObject1, $privateObject2;
    private $propAccessible1, $propAccessible2;

    public function __construct($injectedObject1, $injectedObject2) {
        $this->privateObject1=$injectedObject1;
        $this->privateObject2=$injectedObject2;
    }

    public function __get($property) {
        if (property_exists($this, $property)) return $this->$property;
        else throw new \Exception("Property '$property' does not exist");
    }

    public function __set($property, $value) {
        if (!property_exists($this, $property)) throw new \Exception("Property '$property' is not allowed");
        $this->$property = $value;
        return $this;
    }
}

class Entity2
{
    private $privateObject1, $privateObject2;
    private $data=[];

    public function __construct($injectedObject1, $injectedObject2) {
        $this->privateObject1=$injectedObject1;
        $this->privateObject2=$injectedObject2;
    }

    public function __set($property, $value) {
        $this->data[$property] = $value;
    }

    public function __get($property) {
        if (array_key_exists($property, $this->data)) {
            return $this->data[$property];
        }
        else throw new \Exception("Property '$property' does not exist");
    }
}

1 回复 | 直到 6 年前

Don't Panic 6 年前

你可以稍微修改一下第二种方法。在中定义可访问的密钥 $data ,并检查是否存在 __set() 就像你已经在做了一样 __get() .

class Entity2
{
    private $privateObject1, $privateObject2;
    private $data = [
        'accessible1' => null,
        'accessible2' => null
    ];

    public function __construct($injectedObject1, $injectedObject2)
    {
        $this->privateObject1 = $injectedObject1;
        $this->privateObject2 = $injectedObject2;
    }

    public function __set($property, $value)
    {
        if (array_key_exists($property, $this->data)) {
            $this->data[$property] = $value;
        } else throw new \Exception("Property '$property' does not exist");
    }

    public function __get($property)
    {
        if (array_key_exists($property, $this->data)) {
            return $this->data[$property];
        } else throw new \Exception("Property '$property' does not exist");
    }
}

不过,我并不真正相信在php中严格避免公共属性。如果它们无论如何都可以通过magic方法公开访问,我宁愿将它们声明为public,以便更清楚地说明类是如何工作的。