<?php
 
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)){
            echo 'failed';
        }
        else {
            echo 'matched';
        }
    }
}
 
$foo = new test('abcdefg');
$foo->validate();

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