in this below class i want to use class like with static methods and for use class methods without create new object from parent.
for example:
<?php
class Permission
{
protected $permission = false;
protected $id = 0;
public static function __construct()
{
return new static;
}
public function user( $id )
{
$this->id = $id;
}
public function check()
{
$this->permission = true;
}
public function item( $item )
{
return $item;
}
}
$bar = Permission::user(100)->item("HELLO");
print_r($bar);
this code not working and have problem. how to resolve this class problem?
That will not work because user method is not static, try changing this two methods, and this is good way of generating objects
public function __construct($id)
{
$this->id = $id;
}
public static function user( $id )
{
return new static($id);
}
I'd suggest you a singleton pattern, like this
class Permission
{
static protected $permission = false;
static protected $id = 0;
private static $_instance = null;
private function __construct () { }
public static function getInstance()
{
if (self::$_instance === null) {
self::$_instance = new self;
}
return self::$_instance;
}
public static function user( $userId )
{
self::$id = $userId;
return self::$_instance;
}
public static function check()
{
self::$permission = true;
return self::$_instance;
}
public static function item( $item )
{
return $item;
}
}
$bar = Permission::getInstance()->user(100)->item("HELLO");
print_r($bar);
You can chain methods in 'dynamic' classes by returning $this at the end of method (remember, you have a static).
class A {
public function someMethod()
{
// some code
return $this
}
public function otherMethod()
{
// some code
return $this
}
$a = new A();
$a->someMethod()->otherMethod();
}
Related
I have these related classes:
class cars {
public $cars;
public function addCar($name, $car)
{
$this->cars[$name] = $car;
}
public function getCars()
{
return $this->cars;
}
public function getCar($name)
{
return $this->cars[$name];
}
public function getParams()
{
return $this->params;
}
}
$cars = new cars();
class bmw extends cars {
private static $_instance = null;
protected $params;
function __construct()
{
$this->params['param'] = 'foo';
}
public static function init()
{
if (self::$_instance === null) {
self::$_instance = new self;
}
return self::$_instance;
}
}
$cars->addCar( 'bmw', bmw::init() );
Basically i need to access all child classes from parent class. And use methods defined in parent class on those defined child classes. Parent class should not be modified when adding new child classes.
In the end this should work like this:
foreach( $cars->getCars() as $car )
{
foreach( $car->getParams() as $key => $param )
echo "$key = $param";
}
What is the proper way to do this?
It's really difficult to provide an help since it's not so clear what you're trying to achieve.
It seems to me that you need Registry Class (carDealer), an abstract class with common (for each child) methods and a child (Bmw) of this.
So, something like:
// You seems to need what is called sometimes a Registry.
// Something which deal with keeping and delivering a group of 'related' classes, as a register.
class CarsDealer
{
public $cars;
public function addCar($name, $car)
{
$this->cars[$name] = $car;
}
public function getCars()
{
return $this->cars;
}
public function getCar($name)
{
return $this->cars[$name];
}
}
// then you need a basic contract for each concrete classes
// that will have the same nature and so will extend it
abstract class Car
{
protected $params;
public function getParams()
{
return $this->params;
}
}
// finally the concrete class
class Bmw extends Car
{
public function __construct($params = null)
{
$this->params['param'] = $params;
}
}
$carsDealer = new CarsDealer();
$carsDealer->addCar('bmw', new Bmw('foo'));
foreach ($carsDealer->getCars() as $car)
{
foreach ($car->getParams() as $key => $param) {
echo "$key = $param";
}
}
Please pay attention to some basic rules/good practices/conventions:
class naming, always capitalized
Responsibilities (a class Bmw shouldn't have a method getCars, at least not in this example)
Visibility of method, parameters
http://www.php-fig.org/psr/psr-1/
http://www.php-fig.org/psr/psr-2/
Just one another approach, if you just need get this 'params' :-)
class cars {
public $cars;
public function addCar($name, $car)
{
$this->cars[$name] = $car;
}
public function getCars()
{
return $this->cars;
}
public function getCar($name)
{
return $this->cars[$name];
}
public function getParams($obj)
{
return $obj->params;
}
}
$cars = new cars();
class bmw extends cars {
private static $_instance = null;
protected $params;
function __construct()
{
$this->params['param'] = 'foo';
}
public static function init()
{
if (self::$_instance === null) {
self::$_instance = new self;
}
return self::$_instance;
}
}
$cars->addCar( 'bmw', bmw::init() );
print_r( $cars->getParams($cars->getCar('bmw')));
Trying to use objects that extend singletone, but something I can't do.
How to call method from extended class?
How to show 13 non 12 with singleton?
class SingletonTest
{
protected static $_instance;
private function __construct(){}
private function __clone(){}
public static function getInstance() {
if (null === self::$_instance) {
self::$_instance = new self();
}
return self::$_instance;
}
public function test2(){
return 12;
}
}
class ExtendSingleton extends SingletonTest
{
public function test2() {
return 13;
}
}
$b = ExtendSingleton::getInstance();
echo $b->test2(); //12
You will get what you want if you use static binding keyword "static" instead of "self"
class SingletonTest
{
protected static $_instance;
private function __construct(){}
private function __clone(){}
public static function getInstance() {
if (null === static::$_instance) {
static::$_instance = new static();
}
return static::$_instance;
}
public function test2(){
return 12;
}
}
class ExtendSingleton extends SingletonTest
{
public function test2() {
return 13;
}
}
$b = ExtendSingleton::getInstance();
echo $b->test2(); //13
$a = SingletonTest::getInstance();
echo $a->test2(); //13
exit;
But as You see in the above example this way a class which You will call first to "getInstance" will take place to store its instance in the $_instance field.
There is no way to create a base singleton class and inherit singleton behavior.
public static function getInstance()
{
static $instances = array();
$calledClass = get_called_class();
if (!isset($instances[$calledClass]))
{
$instances[$calledClass] = new $calledClass();
}
return $instances[$calledClass];
}
So this should work for you:
(So first normally functions are public so you can use them if you extend from another class! And the you have to make an object from ExtendSingleton not from SingletonTest since ExtendSingleton exdend's -> SingletonTest and not the other way.)
<?php
class SingletonTest {
protected static $_instance;
public function __construct() {
}
public function __clone() {
}
public static function getInstance() {
if (null === self::$_instance) {
self::$_instance = new self();
}
return self::$_instance;
}
public function test2(){
return 12;
}
}
class ExtendSingleton extends SingletonTest {
public function test2() {
return 13;
}
}
$b = new ExtendSingleton();
echo $b->test2(); //13
?>
Output:
13
I've tested bicccio's solution and it works
class SingletonTest
{
protected static $_instances = [];
private function __construct(){}
private function __clone(){}
public static function getInstance()
{
$calledClass = get_called_class();
if (!isset(self::$_instances[$calledClass]))
{
self::$_instances[$calledClass] = new $calledClass();
}
return self::$_instances[$calledClass];
}
public function test2(){
return 12;
}
}
class ExtendSingleton extends SingletonTest
{
public function test2() {
return 13;
}
}
$b = ExtendSingleton::getInstance();
echo $b->test2(); //13
$a = SingletonTest::getInstance();
echo $a->test2(); //12
You can extend singleton class in php using late static binding the whole process is well discussed in this question.
Creating the Singleton design pattern in PHP5
I have an extended class with an overriden method doSomething().
For some reason the inherited class' method never runs only the base one.
class cDemoClass {
public static function getInstance() {
static $instance = null;
if ($instance === null)
$instance = new cDemoClass();
return $instance;
}
private function __construct() {
}
protected function doSomething() {
echo 'do something';
}
public function call_me() {
$this->doSomething();
}
}
class cDemoClassEx extends cDemoClass {
protected function doSomething() {
echo 'do something differently';
}
}
$baseclass = cDemoClass::getInstance();
$baseclass->call_me();
echo '<br/>';
$extendedclass = cDemoClassEx::getInstance();
$extendedclass->call_me();
result:
do something
do something
The second one should be "do something differently" at least that's what I'm expecting.
Can anyone tell me what I'm doing wrong? Thanks
In this case, you need using late static binding (5.3+). Change in parent method getInstance line :
$instance = new cDemoClass();
to
$instance = new static();
You will get:
do something
do something differently
Read more about this feature here: http://www.php.net/manual/en/language.oop5.late-static-bindings.php
Because cDemoClassEx::getInstance(); is still returning new cDemoClass();. You have to also overwrite the getInstance() method:
class cDemoClass {
public static function getInstance() {
static $instance = null;
if ($instance === null)
$instance = new cDemoClass();
return $instance;
}
private function __construct() {
}
protected function doSomething() {
echo 'do something';
}
public function call_me() {
$this->doSomething();
}
}
class cDemoClassEx extends cDemoClass {
public static function getInstance() {
static $instance = null;
if ($instance === null)
$instance = new cDemoClassEx();
return $instance;
}
private function __construct() {
}
protected function doSomething() {
echo 'do something differently';
}
}
$baseclass = cDemoClass::getInstance();
$baseclass->call_me();
echo '<br/>';
$extendedclass = cDemoClassEx::getInstance();
$extendedclass->call_me();
You have to override with the cDemoClassEx::getInstance() and change this line
$instance = new cDemoClass();
into
$instance = new cDemoClassEx();
You will also need to declare the cDemoClass::__construct() as protected or simply override it in cDemoClassEx.
Bellow is a PHP script.
I tried to implement the Observer pattern (without MVC structure)... only basic.
The error which is encountered has been specified in a comment.
First I tried to add User objects to the UsersLibrary repository. There was a error such as User::update() does not exists or something.
Why is that error encountered? What fix should be applied and how?
interface IObserver {
public function update(IObservable $sender);
}
interface IObservable {
public function addObserver(IObserver $obj);
public function notify();
}
class UsersLibrary implements IObservable {
private $container;
private $contor;
//private $z;
public function __construct() {//IObserver $a) {
$this->container = array();
$this->contor = 0;
echo "<div>[constructing UsersLibrary...]</div>";
$this->addObserver(new Logger());
//$this->z = $a;
}
public function add($obj) {
echo "<div>[adding a new user...]</div>";
$this->container[$this->contor] = $obj;
$this->contor++;
$this->notify();
}
public function get($index) {
return $this->container[$index];
}
public function addObserver(IObserver $obj) {
$this->container[] = $obj;
}
public function notify() {
echo "<div>[notification in progress...]</div>";
foreach($this->container as $temp) {
//echo $temp;
#################################################################
$temp->update(); //--------ERROR
//Fatal Error: Call to a member function update() on a non-object.
#################################################################
}
//$this->container[0]->update();
//$this->z->update($this);
}
}
class User {
private $id;
private $name;
public function __construct($id, $name) {
$this->id = $id;
$this->name = $name;
}
public function getId() {
return $this->id;
}
public function getName() {
return $this->name;
}
}
class Logger implements IObserver {
public function __construct() {
echo "<div>[constructing Logger...]</div>";
}
public function update(IObservable $sender) {
echo "<div>A new user has been added.</div>";
}
}
$a = new UsersLibrary(); //new Logger());
//$a->add(new User(1, "DemoUser1"));
//$a->add(new User(2, "DemoUser2"));
$a->add("Demo");
echo $a->get(0);
//echo $a->get(0)->getName();
Your User class is not implementing interface IObserver and therefore is not forced to have the method update().
You have to instantiate a new User() in order to add it to the UsersLibrary:
$library = new UsersLibrary();
$user = new User(1, "Demo");
$library->add($user);
Also, you are mixing Users and Loggers into your UsersLibrary container. Maybe think about separating the containers for them?
You are passing a string instead of an object in your $a->add() call. You should either pass in an object, or alter the code in UserLibrary::add() to wrap it's argument in an appropriate object (or do an object lookup of it sees a string, for instance find a user with that name).
$user = new User(1, "Demo");
$a = new UsersLibrary();
$a->add($user);
I'm a AS3 coder and i do a bit of php and i am having a hard time doing a static class that can cache variables.
Here's what i have so far :
<?php
class Cache {
private static $obj;
public static function getInstance() {
if (is_null(self::$obj)){
$obj = new stdClass();
}
if (!self::$instance instanceof self) {
self::$instance = new self;
}
return self::$instance;
}
public static function set($key,$value){
self::$obj->$key = $value;
}
public static function get($key){
return self::$obj->$key;
}
}
?>
And i use the following to set my variable into an object of my static class :
<?php
include 'cache.php';
$cache = new Cache();
$cache->set("foo", "bar");
?>
And this is retrieve the variable
<?php
include 'cache.php';
$cache = new Cache();
$echo = $cache->get("foo");
echo $echo //doesn't echo anything
?>
What am i doing wrong ? Thank you
I've adapted #prodigitalson's code above to get something rudimentary that works (and has much room for improvement):
class VarCache {
protected static $instance;
protected static $data = array();
protected function __construct() {}
public static function getInstance() {
if(!self::$instance) {
self:$instance = new self();
}
return self::$instance;
}
public function get($key) {
self::getInstance();
return isset(self::$data[$key]) ? self::$data[$key] : null;
}
public function set($key, $value) {
self::getInstance();
self::$data[$key] = $value;
}
}
Usage
VarCache::set('foo', 'bar');
echo VarCache::get('foo');
// 'bar'
You'll want this class to be available everywhere you need it, and if you want it to persist between requests, I'd consider using Memcached or something similar, which will give you everything you need.
You could alternatively use some SPL functions, like ArrayObject, if you wanted to be clever :)
Try this:
class VarCache {
protected $instance;
protected $data = array();
protected __construct() {}
public static function getInstance()
{
if(!self::$instance) {
self:$instance = new self();
}
return self::$instance;
}
public function __get($key) {
return isset($this->data[$key]) ? $this->data[$key] : null;
}
public function __set($key, $value) {
$this->data[$key] = $value;
}
}
// usage
VarCache::getInstance()->theKey = 'somevalue';
echo VarCache::getInstance()->theKey;