Question

When I try to Override the class variable same way as override the class method in PHP. Like:

class DataMapper {
     protected $_name = null;

     public function printName() {
          echo $this->_name;
     }
}

class Model extends DataMapper {
     protected $_name = 'Ana';
}

$test = new Model();
$test->printName();

It’s print ‘Ana’.

Why PHP can do such a thing like that ? It break the law of object oriented paradigm

Answer 1

It’s not. That’s how PHP is supposed to work. Have a look at PHP Classes and Objects Visibility.

Objects of the same type will have access to each others private and protected members even though they are not the same instances. This is because the implementation specific details are already known when inside those objects.

Because Model extends DataMapper, it has access to its functions, variables and such but it can override them which is what happened. Although your function lives in the DataMapper class, it’s called from (and inherited by) the Model class in which the name is set to Ana.