PHP class attributes and class constants

*Class attributes and class constants

* 1. Class attributes only allow the following types of data to be initialized

* Scalar and array literals: strings, values, constants, arrays , Prototype document (php5.3)

* 2. Not allowed to use: variables, expressions, objects

* 3. Class constants are declared using the keyword const, and access restrictions are not allowed to be set , forced to be public and cannot be changed

* 4. Class constants are attribute classes and do not attribute to one of its instance objects. They must be accessed using classes

* 5. Access class constants To use the range parsing character::, double colon

* Use the keyword self in the class to indicate the current class, and the class name can be used directly externally

define('SITE_NAME','PHP中文网');
class User1 
{
    //声明属性
    private $siteName = SITE_NAME;
    private $name = '老顽童';
    private $email = 'lwt@php.cn';
    private $course = ['php','java','python'];
    const LECTURE = '朱老师';
    //构造方法
    public function __construct($name='',$email='', $siteName='',array $course=[]) 
    {
        //如果传参,则使用新值初始化属性,否则使用默认值
        $name ? ($this->name = $name) : $this->name;
        $email ? ($this->email = $email) : $this->email;
        $siteName ? ($this->siteName = $siteName) : $this->siteName;
        $course ? ($this->course = $course) : $this->course;
        
    }
    
    //查询器
    public function __get($name)
    {
        return $this->$name;
    }
    
    //设置器
    public function __set($name,$value)
    {
        return $this->$name = $value;
    }
    
    //在类中访问类常量,使用self来引用当前类名
    public function getConst()
    {
        //类内部也可以直接使用当前类名
//        return User1::LECTURE;
        //推荐使用self:当类名改变时,不必修改内部对它的引用
        return self::LECTURE;
    }
}