DataMapper for Codeigniter：是否可以一次实例化模型对象并重新使用？

Question

Not trying to spam or advertise here, I value this community and the people that gladly give up their time to answer questions (like myself). I have built an authentication library for Codeigniter called WolfAuth. It currently relies on DataMapper for all database interaction, until further notice.

Each function currently uses code along the lines of the following.

$u = new User;
$u->get_by_id($user_id);

if ( $u->exists() )
{  
    // Do user stuff here  
}

I'm not entirely sure how PHP handles object instantiation, but surely doing this in 50 functions plus can't be good for performance, and if not, adds unnecessary object instantiation. Is it possible to have a global instantiation of each DataMapper model object I am using and re-use in each function?

So something like the following.

class Someclass {

    protected $user;
    protected $group;
    protected $roles;

    public function __construct()
    {
        $this->user  = new User;
        $this->group = new Group;
    }

    public function the_user($user_id)
    {
        $user = $this->user->get_by_id($user_id);

        if ( $user->exists() )
        {
            echo "The user exists!";
        } 
    }

}

Am I just being extremely picky here, or is what I am asking possible and probably the better way to do things for such a large library like I've built?

Answer 1

Yes, you can pass objects as arguments in php.

class Someclass {

protected $user;
protected $group;
protected $roles;

public function __construct()
{
    $this->user  = new User();
    $this->group = new Group();
}

public function get_user($user_id)
{
    if (empty($this->user->id))
    {
        $user = $this->user->get_by_id($user_id);
    }
    else
    {
        $user = $this->user;
    }
    if ( $user->exists() )
    {
        prove_user_exists($user);
        return $user;
    }
    else
    {
        show_error('No User Found');
    }
}

public function prove_user_exists($user)
{
    log_message('info', $user->id);
}

Then, you can just call get_user($user_id) when you need the user - if the user has already been found, then you won't have to call the db again.