preg_match不接受$ this

Question

Am I being stupid or does preg_match() not accept global class variables?

class test{
    private$username,$usernameValidation;
    public function __construct($username){
        $this->username=$username;
        $this->usernameValidation="/^[a-zA-Z0-9]{0,8}$/";
    }
    public function validate(){
       if(!preg_match($this->usernameValidation,$this->username)){
           //failed;
       }
    }
}

Every time I compile a function like this, it seems to tell me the the expression is empty. Seems to work as preg_match("/^[a-zA-Z0-9]{0,8}$/",$this->username);.

Answer 1

You can try keeping regex assignment at class level:

class test {
    const UsernameValidation = '/^[a-zA-Z0-9]{0,8}$/';
    private $username;

    public function __construct($username){
        $this->username=$username;
    }
    public function validate(){
       if(!preg_match(UsernameValidation, $this->username)) {
           //failed;
       }
    }
}