CODEWITHSUNDEEP
phpoop
user1944429
user1944429

Reputation:

PHP change method/function visibility

I am trying to write a PHP class in which I change the visibility of a few methods from protected to public. I believe I remember you can do this in C++, but I did a few searches and I am not coming up with anything for that in PHP. Does anyone know if this is even possible in PHP?

For example, suppose this class:

 class ABC {
     protected function foo() {
          // Do something
     }
  }

  class DEG extends ABC {
      // can I make foo public now?
  }

Upvotes: 8

Views: 9128

Answers (3)

Zsolt Szilagyi
Zsolt Szilagyi

Reputation: 5006

  • You can overwrite a method in a derived class to highten it´s visibility (e.g. protected->public). Make the new function return it´s parent.
  • You cannot do so to limit it´s visibility (e.g. public->protected), but you can implement a method that checks the backtrace for the caller and thwors an exception if it´s a foreign class.
  • You can always use the reflection API to do all kinds of changes to the visibility.

Upvotes: 5

vidit
vidit

Reputation: 6451

Yes, it can be done. Quoting from PHP manual..

The visibility of a property or method can be defined by prefixing the declaration with the keywords public, protected or private. Class members declared public can be accessed everywhere. Members declared protected can be accessed only within the class itself and by inherited and parent classes. Members declared as private may only be accessed by the class that defines the member.

And the example from there as well.. 

class MyClass
{
    public $public = 'Public';
    protected $protected = 'Protected';
    private $private = 'Private';

    function printHello()
    {
        echo $this->public;
        echo $this->protected;
        echo $this->private;
    }
}

$obj = new MyClass();
echo $obj->public; // Works
echo $obj->protected; // Fatal Error
echo $obj->private; // Fatal Error
$obj->printHello(); // Shows Public, Protected and Private

Edit : Yes, you can change visibility of public and protected members. Another example from PHP manual.. 

/**
 * Define MyClass2
 */
class MyClass2 extends MyClass
{
    // We can redeclare the public and protected method, but not private
    protected $protected = 'Protected2';

    function printHello()
    {
        echo $this->public;
        echo $this->protected;
        echo $this->private;
    }
}

$obj2 = new MyClass2();
echo $obj2->public; // Works
echo $obj2->private; // Undefined
echo $obj2->protected; // Fatal Error
$obj2->printHello(); // Shows Public, Protected2, Undefined

?>

Upvotes: -4

Jon
Jon

Reputation: 437336

You can change the visibility of members when deriving from a base class like this:

class Base
{
    protected function foo() {}
}

class Derived extends Base
{
    public function foo() { return parent::foo(); }
}

You can also do the same with properties (redefine a protected property as public).

However, be aware that if the base property is private then you will not actually increase its accessibility but rather declare a new property with the same name. This is not an issue with functions, as if you tried to call a private base method you would immediately get a runtime error.

Upvotes: 14

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