with the follow code:
<?php
class Loader {
private static $instances;
function __construct($class = null) {
return self::instance($class);
}
public static function instance($class) {
if(!isset(self::$instances[$class])) {
self::$instances[$class] = new $class();
}
return self::$instances[$class];
}
}
class Core {
}
$core = new Loader('Core');
print_r($core);
?>
my print_r() return the object Loader instead the object Core, which is instantiated after Loader is constructed.
Thanks for help!
Hm ?
If you do
$core = new Loader('Core');
Then $core is going to be an instance of Loader...
PS : constructors don't return a value.
You don't need to instantiate Loader at all.
Do this :
<?php
class Loader {
private static $instances;
public static function instance($class) {
if(!isset(self::$instances[$class])) {
self::$instances[$class] = new $class();
}
return self::$instances[$class];
}
}
class Core {
}
$core = Loader::instance('Core');
print_r($core);
Or you could do a much simpler :
<?php
function Load($class)
{
static $instances;
if(!isset($instances[$class]))
$instances[$class] = new $class();
return $instances[$class];
}
class Core {
}
$core = Load('Core');
print_r($core);
Related
I have custom class with DI ImapClient $imapClient:
class MailBoxCleaner
{
public function __construct(ImapClient $imapClient)
{
}
}
And there is an facade class:
class ImapConnection {
public function __construct()
{
return new ImapClient();
}
}
I tried to use this like:
$MailBoxCleaner = new MailBoxCleaner(new ImapConnection());
But it does not work.
A constructor never return any data.
You have to create a getter method that return the instance of your ImapClient class, so you inject it in the other class.
Based on your code :
class ImapConnection {
private $imapClient = null;
public function __construct()
{
$this->imapClient = new ImapClient();
}
public function getImapClient(){
return $this->imapClient;
}
}
You can inject :
$idObj = new ImapConnection(); // Instanciation
$MailBoxCleaner = new MailBoxCleaner($idObj->get());
You also can use a "pattern" :
class ImapConnection {
private $instance = null;
private $imapClient = null;
private function __construct()
{
$this->imapClient = new ImapClient();
}
public static function getImapClient(){
if(is_null($this->instance){
$this->instance = new ImapConnection();
}
return $this->instance->get();
}
private function get(){
return $this->imapClient;
}
}
Then, you can use in your code :
$MailBoxCleaner = new MailBoxCleaner(ImapConnection::getImapClient());
Is it possible to declare an object inside another class? The following code keeps giving me an error nexpected 'new' (T_NEW) error.
Class class1{
public function doSomething(){
$var = 3;
return true;
}
}
Class class2{
public $class1 = new class1();
public function doSomethingElse(){
if($class1->doSomething() == true){
return 10;
}else{
return 13;
}
}
}
//$obj = new class2();
I don't really want want to pass in the object through a constructor, because it's used inside other classes, so I'd have to pass it through multiple times. Is there a better method?
Use the Constructor of your class to instantiate the other class.
Class class1
{
public function doSomething()
{
$var = 3;
return true;
}
}
Class class2
{
protected $class1 = null;
public function __construct()
{
$this->class1 = new class1();
}
public function doSomethingElse()
{
if ($this->class1->doSomething() == true) {
return 10;
} else {
return 13;
}
}
}
Yes, but you have to put the initialization in construction method.
Class class2{
public $class1;
public function __construct() {
$this->class1 = new class1();
}
// ...
}
You can only initialize scalar values and arrays, use the constructor:
class Class2 {
public $class1;
public function __construct() {
$this->class1 = new Class1();
}
...
}
There is a public library, and there is a class that can have only one instance in one PHP process, so it's Singleton. The problem is that initialization of this class require some configuration arguments and I can't find good issue to pass them in class constructor.
The only issue I found is:
public static function init($params) {
if(self::$instance) {
throw new Exception(__CLASS__ . ' already initialized');
}
$class = __CLASS__;
self::$instance = new $class($params);
}
public static function getInstance() {
if(!self::$instance) {
throw new Exception(__CLASS__ . ' is not initialized');
}
return self::$instance;
}
But I don't think that it's so really good.Is there any other ideas?
Thanks!
There is example of bad, but working issue:
if(!defined('PSEOUDSINGLETON_PARAM')) {
define('PSEOUDSINGLETON_PARAM', 'default value');
}
class PseoudoSingleton {
protected function __construct($param1 = PSEOUDSINGLETON_PARAM) {
// ...
}
public static function getInstance() {
if(!self::$instance) {
$class = __CLASS__;
self::$instance = new $class();
}
return self::$instance;
}
}
/* on library/utility level */
class nonSingletonService { public function __construct($options){} }
/* on application logic level, so, knows all context */
function getSingleton(){
static $inst;
if (!$inst) $inst=new nonSingletonService(calculateParameters());
return $inst;
}
Sample Singleton implementation:
class MySingleton
{
private static $_INSTANCE = null;
private function __construct()
{
// put initialization code here
}
public static function getInstance()
{
if(self::$_INSTANCE === null) self::$_INSTANCE = new MySingleton();
return self::$_INSTANCE;
}
}
Note that constructor is private, so it can only be called from the class itself.
References to the instance can be only obtained by getInstance call, which creates the object on first call, any subsequent calls will return references to an existing object.
Why are you checking it twice?
Just do the following:
private static function init($params) {
$class = __CLASS__;
self::$instance = new $class($params);
}
public static function getInstance($params) {
if(!self::$instance) {
self::init($params);
}
return self::$instance;
}
That way, you know that you only need to check once and you know you only call init() if the instance is not initialized.
I have this code running on PHP 5.2.6
class Singleton {
static private $instance = false;
private $id = false;
protected function __construct() {
$this->id = uniqid();
}
static public function instance() {
if (!self :: $instance) {
self :: $instance = new self();
}
return self :: $instance;
}
public function get_id() {
return $this->id;
}
}
class Chucknorris extends Singleton {
}
echo "php version = ".phpversion()."<br>";
$singleton = Singleton::instance();
echo get_class($singleton)."<br>";
echo "singleton id = ".$singleton->get_id()."<br>";
$chucknorris = Chucknorris::instance();
echo get_class($chucknorris)."<br>";
echo "chucknorris id = ".$chucknorris->get_id()."<br>";
Here's the output
php version = 5.2.6
Singleton
singleton id = 4ea7dca7d8f23
Singleton
chucknorris id = 4ea7dca7d8f23
When I ask for an instance of Chucknorris, I always get the Singleton one. I'd like to find out a way to extend the Singleton.
I know we can use get_called_class method to do it but it comes only with PHP 5.3. Is there anyway I can extend a Singleton without redefining the design pattern in the extended classes ?
Your best bet in PHP < 5.3 is to use a Singleton Factory:
class Singleton
{
private $id = false;
public function __construct() {
$this->id = uniqid();
}
public function get_id() {
return $this->id;
}
}
class SingletonFactory
{
private static $instance_array = array();
public static function getInstance($class_name)
{
if (!isset(self::$instance_array[$class_name]))
{
self::$instance_array[$class_name] = new $class_name();
}
return self::$instance_array[$class_name];
}
}
class Chucknorris extends Singleton {}
$singleton = SingletonFactory::getInstance('Singleton');
echo get_class($singleton)."<br>";
echo "singleton id = ".$singleton->get_id()."<br>";
$chucknorris = SingletonFactory::getInstance('Chucknorris');
echo get_class($chucknorris)."<br>";
echo "chucknorris id = ".$chucknorris->get_id()."<br>";
The only downside here is that your Singleton constructor is public.. so that's a basic violation of that pattern.
Update:
Here's a version that removes the public constructor (warning: this is getting into messy/hacky/poor design territory)
class Singleton
{
private $id = false;
public function __construct() {
$back = debug_backtrace(false);
if (!isset($back[1]['class']) || $back[1]['class'] != 'SingletonFactory')
{
throw new Exception('Consturctor not available, use SingletonFactory::getInstance("CLASSNAME")');
}
$this->id = uniqid();
}
public function get_id() {
return $this->id;
}
}
class SingletonFactory
{
private static $instance_array = array();
public static function getInstance($class_name)
{
if (!isset(self::$instance_array[$class_name]))
{
self::$instance_array[$class_name] = new $class_name($class_name);
}
return self::$instance_array[$class_name];
}
}
class Chucknorris extends Singleton {}
$singleton = SingletonFactory::getInstance('Singleton');
echo get_class($singleton)."<br>";
echo "singleton id = ".$singleton->get_id()."<br>";
$chucknorris = SingletonFactory::getInstance('Chucknorris');
echo get_class($chucknorris)."<br>";
echo "chucknorris id = ".$chucknorris->get_id()."<br>";
$badchuck = new Chucknorris(); // Exception!
Why don't you simulate the get_class_function if it doesn't exist with 5.3 PHP version ?
This code may answer your question.
if (!function_exists('get_called_class')) {
function get_called_class() {
$bt = debug_backtrace();
$lines = file($bt[1]['file']);
preg_match(
'/([a-zA-Z0-9\_]+)::'.$bt[1]['function'].'/',
$lines[$bt[1]['line']-1],
$matches
);
return $matches[1];
}
}
abstract class Singleton {
private $id = false;
protected function __construct() {
$this->id = uniqid();
}
static public function instance() {
static $instances = array();
$called_class_name = get_called_class();
if (!isset($instances[$called_class_name])) {
$instances[$called_class_name] = new $called_class_name();
}
return $instances[$called_class_name];
}
public function get_id() {
return $this->id;
}
}
class Chucknorris extends Singleton {}
class Brucelee extends Singleton {}
echo "php version = ".phpversion()."<br>";
$chucknorris = Chucknorris::instance();
echo get_class($chucknorris)."<br>";
echo "chucknorris id = ".$chucknorris->get_id()."<br>";
$brucelee = Brucelee::instance();
echo get_class($brucelee)."<br>";
echo "brucelee id = ".$brucelee->get_id()."<br>";
You can redefine just the getinstance method (and the instance itself) in Chucknorris to get an instance of it instead of the parent, but I'm not exactly sure what your end goal is. Just change the extending class to:
class Chucknorris extends Singleton {
static private $instance = false;
static public function instance()
{
if (!self :: $instance) {
self :: $instance = new self();
}
return self :: $instance;
}
}
Is this what you want? And if so - what is the reason you want it? I could think of a few, but would be glad if you share you goal.
Your code will most likely work if you move static private $instance = false; to the subclass and make it protected instead of private.
You also need to replace self:: with static:: so the static var is set in the subclass.
This requires PHP 5.3 - however, this shouldn't be a problem because PHP 5.2 reached end-of-life/support (that includes security updates!) as of january 2011!
hello im still on learning mvc by makeing one, and today i realize that i have a miss on how things work.
class Framework
{
function __construct()
{
require 'libraries/language/l.php';
/*
$l['hello'] = 'hello';
$l['helloworld'] = 'helloworld';
etc
*/
}
}
class Controller extends Framework
{
function index()
{
#missing ?
echo $l;
}
}
ok the first question is how can i echo $l from my controller files ? is there a way to do that ?
edit* same for this.
function library( $lib ){
if (file_exists('libraries/lib.'. $lib .'.php')) {
require 'libraries/lib.'. $lib .'.php';
if (class_exists($lib)) {
$class = ucfirst($lib);
$$lib = new $class;
return TRUE;
}
if (!class_exists($lib)) {
return FALSE;
}
}
}
thanks for looking in.
Adam ramadhan
Pass the data through object protected properties:
class Framework
{
protected $l = array();
function __construct()
{
require 'libraries/language/l.php';
$this->l['hello'] = 'hello';
$this->l['helloworld'] = 'helloworld';
}
}
class Controller extends Framework
{
function index()
{
echo $this->l['hello'];
}
}
Well, that means for each Controller instance, you are going to keep a big array inside it.
Actually, you can make a singleton class that provides translation for text:
class Language
{
private static $instance;
public $l = array();
private function __construct() {
require 'libraries/language/l.php';
$this->l = $l;
}
public static function getInstance() {
if (!isset(self::$instance)) {
$c = __CLASS__;
self::$instance = new $c;
}
return self::$instance;
}
}
And you can have a shorthand function for it:
function l($text) {
return Language::getInstance()->l[$text];
}
And then use it:
echo l('hello') . "\n";