如何从PHP中的其他类使用STATIC方法访问类属性？

Question

the question title seems pretty confusing, but this is what i want to achieve.

i have two classes

1. Category
2. Validation

In Category Class i have the following Class Property

public  $error;    //holds all errors in an array.
private $dbh;      //Database object Handle(PDO).
private $validate; //Holds Validation Object
private $data = array('categoryName',
                      'subCategoryName',
                      'prefix',
                      'categoryId',
                      'subCategoryId');

in Validation Class i have defined a method.

public function required($fields = array()) {
    foreach($fields as $field) {
        if(empty(__CLASS__::data[$field])) {

        }
    }
}

now when i call the method $this->validate->required() within the class Category it should check the condition if $data[field] of Category class is empty or got any value in it. hence i have used the following syntax which does not seems to work. if(empty(__CLASS__::data[$field]))what the condition should check is if the class property $data of the class it is being called from (it is class Category in this case) is empty or not. what is the correct syntax for fetching the class property dynamically?

thank you..

Answer 1

Give your Category instance as parameter to your validation function. You should have something like this:

public function required($category, $fields = array()) {
    foreach($fields as $field) {
        if(empty($category->data[$field])) {

        }
    }
}

$this->validate->required($this);

Also you do not use a static method, as mentioned in your questions headline in your example. If you have a static function in Validation you would call it like this:

Validation::required($this);

In this case, you do not need a reference to a Validation instance in your Category class at all.