从基类返回类的实例

Question

I'd like to create an object like so:

class Obj extends BaseModel {

    public function doSomething() {
        // do some stuff with the instance
    }
}



class BaseModel {

    public static function find($id){
        // retrieve object from database and return instance of Obj class
    }
}

So i can achieve the following:

$obj1 = Obj::find(1);
$obj1->doSomething();

How can I create this so that the static method from the base class returns an instance of the Obj class?

(similar to how Laravel handles objects)

Answer 1

In your base model, you can get the class of the children that's been called with get_called_class.

class Obj extends Base{

    private $id;

    public function __construct($id){
        $this->id = $id;
    }

    public function getId(){
        return $id;
    }

}

class Base{

    public static function find($id){
        $class = get_called_class();
        return new $class($id);
    }

}

Example

$obj = Obj::find(1);

var_dump of $obj

object(Obj)#1 (1) {
  ["id":"Obj":private]=>
  int(1)
}