PHP access Control

Access control

Access control is implemented by keyword public,protected and private. Class members that are defined as public can be accessed from anywhere. A class member that is defined as protected can be accessed by itself and its subclasses and parent classes. A class member that is defined as private can only be accessed by the class in which it is defined.

Class properties must be defined as public , protected , and private . To be compatible with previous versions of PHP5, if the VAR definition is used, it is considered public.

Class Car {

$speed = 10; The error attribute must define access control

var $speed = 10; Equivalent to Public

Public $name; Defining common attributes

}

A method in a class can be defined as public, private, or protected. If these keywords are not set, the method defaults to public.

Class Car {

Default is common method

function TurnLeft () {

}

}

If the constructor is defined as a private method, it is not allowed to instantiate the object directly, which is typically instantiated by a static method, which is often used in design mode to control the creation of objects, such as a singleton pattern that only allows a globally unique object.

Class Car {

Private Function __construct () {

Echo ' object create ';

}

private static $_object = null;

public static function getinstance () {

if (empty (Self::$_object)) {

Self::$_object = new Car (); Internal methods can call private methods, so you can create objects here

}

return self::$_object;

}

}

$car = new car (); Direct instantiation of objects is not allowed here

$car = Car::getinstance (); Using static methods to obtain an instance

PHP access Control