I am using Drupal 7 and I am using my custom module's .info file along with the "files[] = ...." directive to allow autoloading of my classes when required. Each class only contains static public functions and everything is working nicely when these functions are called from a function of the general scope.
Working example:
If I go to /devel/php and call the function ClassTwo::getValue() everything is executed without error.
Example with error:
If I call the function ClassTwo::getValue() from within another autoloaded function ClassOne::generate() an exception is thrown that the class ClassTwo() doesn't exist. The error is solved if I specifically include the file containing the class ClassTwo.
I don't believe it has something to do with Drupal's autoloading mechanism though. Is my scenario allowed in PHP 5.3?
For better clarification I have added below example code. That's the nearest I can provide to working code.
mymodule/mymodule.info
name = "MyModule"
core = "7.x"
files[] = "includes/plugins/ClassOne.inc"
files[] = "includes/plugins/ClassTwo.inc"
mymodule/mymodule.module
function mymodule_page_callback() {
return ClassOne::generate();
}
mymodule/includes/plugins/ClassOne.inc
Class ClassOne {
static public function generate() {
$value = ClassTwo::getValue();
// Process $value
return $value;
}
}
mymodule/includes/plugins/ClassTwo.inc
Class ClassTwo {
static public function getValue() {
// Somehow retrieve the value.
return $value;
}
}
UPDATE: Using Drupal's xautoload module with PSR-4 everything works incredibly fine and I have turned to this method as a solution. If anyone has an answer though, other than PSR-0/PSR-4, I would like to know it.
I am interested in learning autoloading, but new to PHP.
I am reading the book "PHP in Action" which writes the autoload method like
function __autoload($className) {
include_once __autoloadFilename($className);
}
function __autoloadFilename($className) {
return str_replace('_','/',$className).".php";
}
I want to pack these methods in a class. will it be better to pack them in an abstract class?
Or in normal class and including it in index.php?
How effeciently I can use the autoloading feature?
Thanks
Securing an autoloader, ensure:
That the file you try to load is actually a file. include is pretty much like eval. For example disallow url inclusion via the php configuration.
That the classname is actually a syntactically correct classname. Could be helpful to secure things ;)
You can also white-list namespaces and/or classnames that are appropriate for your concrete autoloader.
Create a class as an autoloader, you must not take the static way, you can just assign any callback with spl_autoload_register, so you can register multiple autoloaders.
Some quickly written autoloader class stub:
class MyAutoloader
{
public function __construct()
{
$this->register();
}
public function register()
{
spl_autoload_register(array($this,'autoload'));
}
public function autoload($classname)
{
if ($this->isInvalidClassName($classname)) return;
$file = $this->getFileForClassName($classname);
if ($this->isInalidFile($file)) return;
require $file; // bail out fatally.
}
...
}
$myAutoloader = new MyAutoloader();
It's up to you. I use a dedicated class called Loader with a method called load(), which I activate with:
spl_autoload_register( 'Utility_Loader::load' );
i just got some more questions while learning PHP, does php implement any built in plugin system?
so the plugin would be able to change the behavior of the core component.
for example something like this works:
include 'core.class.php';
include 'plugin1.class.php';
include 'plugin2.class.php';
new plugin2;
where
core.class.php contains
class core {
public function coremethod1(){
echo 'coremethod1';
}
public function coremethod2(){
echo 'coremethod2';
}
}
plugin1.class.php contains
class plugin1 extends core {
public function coremethod1(){
echo 'plugin1method1';
}
}
plugin2.class.php contains
class plugin2 extends plugin1 {
public function coremethod2(){
echo 'plugin2method2';
}
}
This would be ideal, if not for the problem that now the plugins are dependable on each other, and removing one of the plugins:
include 'core.class.php';
//include 'plugin1.class.php';
include 'plugin2.class.php';
new plugin2;
breaks the whole thing...
are there any proper methods to doing this?
if there are not, them i might consider moving to a different langauge that supports this...
thanks for any help.
edit:
obviously it is my understanding that is lacking, so here is a
attempt at a clarification.
core.class.php contains anything...
plugin1.class.php contains anything...
plugin2.class.php contains anything...
include 'core.class.php';
include 'plugin1.class.php';
include 'plugin2.class.php';
$core = new core;
$core->coremethod1();//outputs plugin2method1
whereas:
include 'core.class.php';
include 'plugin2.class.php';
$core = new core;
$core->coremethod1();//outputs plugin1method1
I'm interested in any implementation, even one not involving classes
for example
include 'core.php';
//does core stuff
include 'core.php';
include 'plugin1';
//does extended core stuff
include 'core.php';
include 'plugin2';
//does extended core stuff
include 'core.php';
include 'plugin2';
include 'plugin1';
//does very extended core stuff
including a file needs to change the application behavior. for it to have any meaning.
I do not know what this is called either, so point me at the proper naming if there is any.
You are misusing the term "plugin". A plugin is generally a package of code that extends or alters the base functionality of a system - to make actual PHP plugins (which in the PHP world are called extensions) you'd be writing C or C++.
What you're describing here is merely including classes or class trees into the current execution for usage. And there is a way to bring them into the current execution context 'automatically', and that's via the autoload system.
If, after you've read the documentation on autoloading, you are still unsure of how to move forward, comment here and I will help you along.
EDIT
Ok, I see what you're after. You can't do exactly what you're after. When you execute new core; an instance of the class core will be returned - you can't modify that at all.
However, if you are willing to modify how you create instances of core, then I think I have something that could work for you, and it might look something like this.
class core {
public function coremethod1(){
echo 'coremethod1';
}
public function coremethod2(){
echo 'coremethod2';
}
/**
* #return core
*/
final public static function create()
{
// listed in order of preference
$plugins = array( 'plugin2', 'plugin1' );
foreach ( $plugins as $plugin )
{
if ( class_exists( $plugin ) )
{
return new $plugin();
}
}
return new self;
}
}
class plugin1 extends core {
public function coremethod1(){
echo 'plugin1method1';
}
}
class plugin2 extends plugin1 {
public function coremethod2(){
echo 'plugin2method2';
}
}
$core = core::create();
// test what we have
echo get_class( $core ), '<br>'
, $core->coremethod1(), '<br>'
, $core->coremethod2()
;
If your only concern is that not including plugin1 will create an error, then you can resort to autoloading to have plugin2 load plugin1 automatically:
From the comments in the PHP Manual on spl_autoload
// Your custom class dir
define('CLASS_DIR', 'class/')
// Add your class dir to include path
set_include_path(get_include_path().PATH_SEPARATOR.CLASS_DIR);
// You can use this trick to make autoloader look
// for commonly used "My.class.php" type filenames
spl_autoload_extensions('.class.php');
// Use default autoload implementation
spl_autoload_register();
If, however, you are looking for a traits/mixin-like feature, then the answer is no. PHP does not support this as of now. At least not without patching the core or resorting to these two APIs you do not want to use in production code.
The proper way to change how an object behaves at runtime would be to use Decorators:
$class = new BasicCache( new BasicValidators ( new Basic ) );
or Strategy patterns:
$class = new Basic;
$class->setStrategy(function() { return 'foo'} );
echo $class->callStrategy(); // foo
$class->setStrategy(function() { return 'bar'} );
echo $class->callStrategy(); // bar
See http://sourcemaking.com/design_patterns for the most common patterns.
EDIT Here is an example of how to create plugins with decorators. Assume, we have a game of some sort where some non-player characters walk around in a virtual space and greet the main character from time to time. That's all they do right now. We want some variation on how they greet though, which is why we need our plugins/decorators in this scenario.
First we create an interface that defines some methods any object able to greet should have. We don't care about what it does when these methods are invoked on a specific object. We just want to make sure that the methods are available and that they are called with a clearly defined input:
interface GreetInterface
{
public function greet($name);
public function setGreeting($greeting);
}
An interface is basically a contract any implementing object must fulfill. In our case, the contract says, if you are an object that can greet, you have to have two methods. Implement them any way you like, but have these methods.
Let's build our non-player character classes now, implementing this interface
class Dude implements GreetInterface
{
protected $greeting = 'hello';
public function greet($name)
{
return sprintf('%s %s', $this->greeting, $name);
}
public function setGreeting($greeting)
{
$this->greeting = $greeting;
return $this;
}
}
That's pretty straigtforward I guess. The Dude class just defines the two methods from the interface. When greet() is called, it will fetch the string stored in greeting and prepend to the param passed to the greet method. The setGreeting method allows us to change the greeting at runtime. Note: you could add a getter as well (I was just lazy)
Now on to the plugins. We will create an abstract GreetPlugin class to contain some shared boilerplate code, simply because we don't want to duplicate code in our actual plugins. The abstract plugin class will implement the GreetInterface, so we can make sure all subclasses implement the interface too.
Since Dude already implements the interface as well, we could have the plugins extend Dude, but that would be conceptually wrong, because extending creates an is-a relationship, but a plugin is not a Dude.
abstract class GreetPluginAbstract implements GreetInterface
{
protected $inner;
public function __construct(GreetInterface $inner)
{
$this->inner = $inner;
}
public function setGreeting($greeting)
{
$this->inner->setGreeting($greeting);
return $this;
}
public function greet($name)
{
return $this->inner->greet($name);
}
}
The plugin class accepts one argument when initialized: any class implementing the GreetInterface. The TypeHint makes sure, the class fulfills the contract. That's required, because, as you can see in the code, our plugins will need to call the methods in the interface on the class passed through the constructor. If we had extended from Dude, we would now be able to wrap dudes into dudes, which is a bit odd. Another reason for not doing it.
Now on to the first plugin. We want some of our dudes to speak with a fancy french accent, which means they use âccénts all over the place, but cannot pronounce a proper h. Disclaimer: yes, I know that's a cliche. Please bear with my examples
class FrenchPlugin extends GreetPluginAbstract
{
public function greet($name) {
return str_replace(array('h', 'e'), array('', 'é'),
$this->inner->greet($name));
}
}
Since the Plugin extends the abstract plugin, we can now focus on the actual code that modifies how a regular dude would do his greeting. When greet() is called, we call greet() on the wrapped element and then remove all h characters and turn all es into és. Everything else is unmodified abstract behavior.
In another plugin, we want to change the wording of the greeting, so we have some dudes say Heya, instead of just Hello. Just to add some variation.
class EasyGoingPlugin extends GreetPluginAbstract
{
protected $inner;
public function __construct(GreetInterface $inner) {
$this->inner = $inner->setGreeting('heya');
parent::__construct($inner);
}
}
This way we only override the constructor, because the greet method should just return whatever it will be. So we call the setGreeting method on the object passed to this plugin. Because the object has to implement the GreetInterface, we can be sure this works.
Note that I am assigning the return value of setGreeting as the inner object. This is possible because I return $this, whenever setMethod is called. This cannot be enforced through the interface, so you cannot rely on this form the interface. I just added it to show another technique: method chaining.
With two plugins done, we feel we have enough variation. Now we only need a convenient way to create Dudes. For that we create a small class like this:
class DudeBuilder
{
public static function build()
{
$dude = new Dude();
$decorators = func_get_args();
foreach($decorators as $decorator) {
$decorator .= "Plugin";
// require_once $decorator;
$dude = new $decorator($dude);
}
return $dude;
}
}
Note: I always mix up Builder and AbstractFactory, so if the above is a Factory, well, then it's a factory. Check out the design patterns links I gave earlier on ;)
All this Builder does, is create a regular dude and then wrap/decorate it into/with whatever plugins we tell it to use and than return it. Because the builder encapsulates no own state, we make the build method static.
For this example I assume you used the autoloading code I gave right on top. If not, you can include the plugin files in the foreach loop. Lazy loading them only when they are needed will give you a few microseconds faster load times over including them all on top. Hopefully, this also explains what I meant in the various comments when I argued the behavior should not be controlled by a file inclusion. The file inclusion is just a necessity. You cannot use a class that is not know to PHP. But that the class is actually used, is controlled by our code alone, by passing in the plugin names to the build method.
Let's do this now
$regularDude = DudeBuilder::build();
$frenchDude = DudeBuilder::build('French');
$easygoingDude = DudeBuilder::build('EasyGoing');
$frenchEasyGoingDude = DudeBuilder::build('French', 'EasyGoing');
This is effectively the same as doing:
$regularDude = new Dude;
$frenchDude = new FrenchPlugin(new Dude);
$easygoingDude = new EasyGoingPlugin(new Dude);
$frenchEasyGoingDude = new FrenchPlugin(new EasyGoingPlugin(new Dude));
With just two plugins, we can now create three types of Dudes. Let's have them greet you:
echo $regularDude->greet('Yuri'), PHP_EOL,
$frenchDude->greet('Yuri'), PHP_EOL,
$easygoingDude->greet('Yuri'), PHP_EOL,
$frenchEasyGoingDude->greet('Yuri'), PHP_EOL;
// gives
hello Yuri
éllo Yuri
heya Yuri
éya Yuri
We can now create additional plugins to decorate our basic classes with. If for some reason, you decide your game should have talking horses or cars as well, you could also create a class Car or Horse and have it implement the greet interface too and add a Builder for them. You can then reuse the plugins to create French EasyGoing Cars or Horses.
PHP core can be extended with PECL extensions (which are C++, I believe).
Core functions can be overridden (if you have the APD PECL extension installed) with override_function
User functions can be executed with call_user_func.
Maybe if you could explain what you are planning, we'd be able to offer a better answer?
Your code is breaking because plugin2 extends plugin1, and you're not including the plugin1 class. Why not make class plugin2 extend core? That seems to be what you're going for.
I am fairly new to OO programming...
I am building what will eventually turn out to be a large library of classes to be used throughout my site. Clearly, loading the entire library on every page is a waste of time and energy...
So what I would like to do is require a single "config" php class file on each page, and be able to "call" or "load" other classes as needed - thus extending my class according to my needs.
From what I know, I can't use a function in the config class to simply include() other files, because of scope issues.
What are my options? How do developers usually handle this problem, and what is the most stable?
You can use __autoload() or create an Object Factory that will load the files required when you need them.
As an aside, if you're having scope issues with your library files, you should probably refactor your layout. Most libraries are sets of classes that can be instantiated in any scope.
The following is an example very basic object factory.
class ObjectFactory {
protected $LibraryPath;
function __construct($LibraryPath) {
$this->LibraryPath = $LibraryPath;
}
public function NewObject($Name, $Parameters = array()) {
if (!class_exists($Name) && !$this->LoadClass($Name))
die('Library File `'.$this->LibraryPath.'/'.$Name.'.Class.php` not found.');
return new $Name($this, $Parameters);
}
public function LoadClass($Name) {
$File = $this->LibraryPath.'/'.$Name.'.Class.php'; // Make your own structure.
if (file_exists($File))
return include($File);
else return false;
}
}
// All of your library files should have access to the factory
class LibraryFile {
protected $Factory;
function __construct(&$Factory, $Parameters) {
$this->Factory = $Factory;
}
}
Sound like you want autoload and spl_autoload_register if you are using classes from 3rd party libraries.
I am planning to use PHP's autoload function to dynamicly load only class files that are needed. Now this could create a huge mess if every single function has a seperate file, So I am hoping and asking is there a way to have related classes remain in 1 class file and still be auto-loaded
function __autoload($class_name){
include('classes/' . $class_name . '.class.php');
}
Let's say there is a class name animals and then another class named dogs. Dogs class extends animals class, now if I were to call the dogs class but NOT call the animals class, would the animals class file still be loaded?
Have you considered explicit definitions of your class locations? Sometimes it makes a lot of sense to group related classes.
Here is a proven way of handling it.
This code is placed in an auto_prepend_file (or included first)
class Import
{
public static $_AutoLoad = array();
public static $_Imported = array();
public static function Load($sName)
{
if(! isset(self::$_AutoLoad[$sName]))
throw new ImportError("Cannot import module with name '$sName'.");
if(! isset(self::$_Imported[$sName]))
{
self::$_Imported[$sName] = True;
require(self::$_AutoLoad[$sName]);
}
}
public static function Push($sName, $sPath)
{
self::$_AutoLoad[$sName] = $sPath;
}
public static function Auto()
{
function __autoload($sClass)
{
Import::Load($sClass);
}
}
}
And in your bootstrap file, define your classes, and what file they are in.
//Define autoload items
Import::Push('Admin_Layout', App::$Path . '/PHP/Admin_Layout.php');
Import::Push('Admin_Layout_Dialog', App::$Path . '/PHP/Admin_Layout.php');
Import::Push('FileClient', App::$Path . '/PHP/FileClient.php');
And lastly, enable AutoLoad by calling
Import::Auto()
One of the nice things is that you can define "Modules":
Import::Push('MyModule', App::$Path . '/Module/MyModule/Init.php');
And then load them explicitly when needed:
Import::Load('MyModule');
And one of the best parts is you can have additional Import::Push lines in the module, which will define all of its classes at runtime.
if I were to call the dogs class but
NOT call the animals class, would the
animals class file still be loaded?
Yes. When you load an class that extends another class, PHP must load the base class so it knows what it's extending.
re: the idea of storing multiple classes per file: This will not work with the autoload function you provided. One class per file is really the best practice, especially for autoloaded classes.
If you have more than one class in a file, you really shouldn't attempt to autoload any classes from that file.
Yes it will load unless you don't include/require the class file.
You have to always import any files that contain needed PHP code. PHP itself can't guess the name you gave to your class file. Unlike Java for instance, PHP doesn't have any file naming requirements for classes.
The common way so solve this problem is to group related classes in one single file. Creating a "module".
There's a workaround, I've just used it and it seems to work:
Let's assume we have an autoloaded class called animals stored in animals.class.php. In the same file you could have other classes that extends animals
class animals{
static function load(){
return true;
}
}
class dogs extends animals{
}
class cats extends animals{
}
Now... when you need to use your class dogs you need PHP autoload it's parent class (and doing this you're sure it will parse also all the extendend classes inside the same file) so you just have to write:
animals::load();
$fuffy = new dogs();