Define data members within constructor

Question

I have got this little snippet of code, I want to be able to define each array element as a new data member.

class Core_User
{
     protected $data_members = array(
         'id'               =>  '%d',
         'email'            => '"%s"',
         'password'         => '"%s"',
         'title'            => '"%s"',
         'first_name'       => '"%s"',
         'last_name'        => '"%s"',
         'time_added'       =>  '%d' ,
         'time_modified'    =>  '%d' ,
         );

    function __construct($id = 0, $data = NULL)
    {
        foreach($this->data_members as $member){
           //protected new data member
        }

    }

Answer 1

What you want to achieve is possible, however you won't be able to make the new properties protected (as this is only possible for predefined members).

function __construct($id = 0, $data = NULL)
{
    foreach($this->$data_memebers as $name => $value ){
       $this->$name = $value;
    }
}

Note the use of the $ before name in $this->$name: This makes PHP use the current value of the $name variable as property.

Answer 2

//protected new data member

You won't be able to create a non-public property at runtime. If protected is paramount, you can declare a protected array or object and insert key/values into it in the constructor

Answer 3

1. Always use $this when you want to access object's members (it should be $this->data_members in constructor).

2. You can try defining magic methods __get & __set (I'm not sure if they can be protected though). :

   protected function __get($name){                  
    if (array_key_exists($name,$this->data_memebers))
    {
        return $this->data_memebers[$name];
    }         
    throw new Exception("key $name doesn't not exist");  
   }  
   protected function __set($name,$value){
    if (array_key_exists($name,$this->data_memebers))
    {
        $this->data_memebers[$name] = $value;
    }
    throw new Exception("key $name doesn't not exist");
   }