The visibility of a property or method can be defined by prefixing the
declaration with the keywords: public, protected or private. Public
declared items can be accessed everywhere. Protected limits access to
inherited and parent classes (and to the class that defines the item).
Private limits visibility only to the class that defines the item.
$obj = new MyClass(); echo $obj->public; // Works echo $obj->protected; // Fatal Error echo $obj->private; // Fatal Error $obj->printHello(); // Shows Public, Protected and Private
/** * Define MyClass2 */ class MyClass2 extends MyClass { // We can redeclare the public and protected method, but not private protected $protected = 'Protected2';
$obj2 = new MyClass2(); echo $obj->public; // Works echo $obj2->private; // Undefined echo $obj2->protected; // Fatal Error $obj2->printHello(); // Shows Public, Protected2, not Private
?>
Note:
The PHP 4 method of declaring a variable with the
var keyword is no longer valid
for PHP 5 objects. For compatibility a variable declared
in php will be assumed with public visibility, and a
E_STRICT warning will be issued.
Class methods must be defined with public, private, or protected. Methods
without any declaration are defined as public.
Example 19-10. Method Declaration
<?php /** * Define MyClass */ class MyClass { // Contructors must be public public function __construct() { }
// Declare a public method public function MyPublic() { }
// Declare a protected method protected function MyProtected() { }
// Declare a private method private function MyPrivate() { }
// This is public function Foo() { $this->MyPublic(); $this->MyProtected(); $this->MyPrivate(); } }
$myclass = new MyClass; $myclass->MyPublic(); // Works $myclass->MyProtected(); // Fatal Error $myclass->MyPrivate(); // Fatal Error $myclass->Foo(); // Public, Protected and Private work
/** * Define MyClass2 */ class MyClass2 extends MyClass { // This is public function Foo2() { $this->MyPublic(); $this->MyProtected(); $this->MyPrivate(); // Fatal Error } }
$myclass2 = new MyClass2; $myclass2->MyPublic(); // Works $myclass2->Foo2(); // Public and Protected work, not Private ?>
