php psr autoload ambiguity - php

I am working on a php sdk rewrite project and the client wants to get PSR standards done. I am looking at the standards page here
https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-0.md
One thing what i am not able to understand, if i use name spaces in my class do i still need to use include or require or use. I mean the whole reason of autoload beats the purpose right ?
For example, say i have a class this way,
namespace Employee\Department;
Class Department
{
//code
}
and i have another class which uses this class by extending it,
namespace Employee\community;
Class Community extends Department
{
//code
}
so does the above code make it to psr-0 standard considering that i have an autoload function exactly thats on the link above.

The second example is going to assume Department is in the Community namespace so in this case you would need a use statement. Also both of your examples would use the namespace Employee not Employee\Whatever for example lets assume the following layout:
Employee/
Community.php
Community/
Manager.php
Department.php
Department/
Manager.php
Then we would see the class/namespaces like the following
namespace Employee;
class Department {
}
///////////
namespace Employee;
class Community extends Department {
}
/////////////
namespace Employee\Department;
class Manager {
}
/////////////
namespace Employee\Community;
use Employee\Department\Manager as BaseManager;
Class Manager extends BaseManager {
}

For your understanding, autoloading works by registering the autoload function in the autoload stack via spl_autoload_register; this allows the function to be invoked whenever a new Class() statement is executed (more info).
On the other hand, the FIG standard for autoloading, PSR-0, defines how a namespace will be translated into a filename by a PSR-0 autoloader function. For example, given the namespace Vendor\Foo, the autoloader will look for the file Vendor/Foo.php having the following code
namespace Vendor;
class Foo
{
public function do()
{
echo "Foo";
}
}
Therefore, following the mandatory requirements, a PSR-0 compliant namespace resolves to the correct PHP file which could otherwise have been included using a require or include.

If I read your intentions correctly, you just need the following namespace in both code snippets:
namespace Employee;
Of course, this is not a PSR-0 namespace because there is no vendor name (unless your vendor name is 'Employee'). Anyway, using this namespace in your two code snippets will work fine.
However, if you intended to keep them in separate namespaces, then the autoloader won't figure out Department in extends Department in the second snippet. You will have to either import the namespace or explicitly specify it as so:
namespace Employee\community;
class Community extends Employee\Department\Department
{
//code
}
I imagine that you did not expect the full class names from your snippets to be Employee\Department\Department, and that is why I first suggested keeping the same namespace for your purposes.

Related

Override object creation with same class in another namespace

I'm trying to trick PHP into taking a class from another namespace when trying to create a specific class.
I have two class called "page", the first is in the Core namespace:
namespace Core;
class Page {...}
The second inherits from Core\Page, but adds a few things. It is in the Addons namespace.
namespace Addons;
class Page extends \Core\Page{...}
The reason I want to do this is because I want to build my system with an easy addon engine. Whenever I want, I can add a line in an XML file that tells the autoloading function to take the class in the addon namespace instead of the core namespace.
However, when I try to do this :
spl_autoload_register('loadClass');
public function loadClass(string $className)
{
if (Addon_exist_and_is_registered($className))
{
require "/Addons/$className.php";
}
else
{
require "/Core/$className.php";
}
}
$page = new \Core\Page(); <-- error here
I get an error saying that the class \Core\Page cannot be found in the file Addons\Page.php. This is normal behaviour since the class is not in the same namespace and as such, the fully qualified name cannot find the right class.
Is it possible to trick PHP into thinking that a child class in another namespace is actually the right class? I tried this for the addons class;
namespace Core;
class Page extends \Core\Page{...}
But it breaks the inheritance as you cannot inherit yourself.
Ignore that the classes have the "same name". Because they don't. One class is called Core\Page, the other is called Addons\Page. Those are their names, their fully qualified names to be exact. It's as much a difference as Foo and Bar. If you tell PHP to instantiate Core\Page, then it's going to do that; you can't "trick" it into instantiating Addons\Page, since that's an entirely different class name.
Don't try to "trick" anyone, make your system actually extensible and explicitly allow overriding of class names:
$class = 'Core\Page';
if (...) {
$class = 'Addons\Page';
}
$page = new $class;

Attempted to load class "ClassName" from namespace (...). Even though namespace is imported

I have a Symfony project to which I added some non-symfony php files containing various classes. But for some reason the classes are not loaded when loading the website, even though the IDE sees them properly.
So, I have a class that needs other classes:
namespace rootspace\FrontBundle\Controller;
use rootspace\FrontBundle\Networks\TwitterOAuth;
use Symfony\Bundle\FrameworkBundle\Controller\Controller;
use Sensio\Bundle\FrameworkExtraBundle\Configuration\Route;
use Sensio\Bundle\FrameworkExtraBundle\Configuration\Template;
class TwitterController extends Controller
{
public function connectAction(){
// The TwitterOAuth instance
$connection = new TwitterOAuth('abc', '123');
}
}
And then the class which fails to load (that needs yet another file)
namespace rootspace\FrontBundle\Networks;
/* Load OAuth lib. You can find it at http://oauth.net */
//require_once('OAuth.php'); -- should this be commented out?
/**
* Twitter OAuth class
*/
class TwitterOAuth {
/* Contains the last HTTP status code returned. */
}
Lastly, the third file
namespace rootspace\FrontBundle\Networks;
use Symfony\Component\Config\Definition\Exception\Exception;
class OAuthConsumer
{
public $key;
public $secret;
}
(...)
I assume the actual filenames don't matter, right? Nor their structure? PhpStorm sees all the classes properly, I can right-click through them, but it fails when deployed.
Thanks for help
Edit - the whole error message says
Attempted to load class "TwitterOAuth" from namespace "rootspace\FrontBundle\Networks" in D:\Dropbox\project\src\rootspace\FrontBundle\Controller\TwitterController.php line 15. Do you need to "use" it from another namespace?
This is because Symfony's autoloader follows PSR standards (PSR-0, PSR-4) which says that fully qualified (with namespace) class name translates to file location and name. So in fact file names does matter.
So in your case rootspace\FrontBundle\Networks\TwitterOAuth class should be located in rootspace/FrontBundle/Networks directory in file called TwitterOAuth.php
If classes you are using does not follow PSR standards you can also register them manually in app/autoloader.php file
Check these for more info:
How can I add a namespace to Symfony 2.1?:
How to autoload class
And check this answer
I forgot to add a .php extension to my filename

PHP Extending Class one Folder Back

I have a base abstract class, say Base.php located at /lib/Helper/Base.php. Now, I have another class, say Awesome.php located at /lib/Helper/Awesome/Awesome.php, and this class needs to extend Base.
I have defined my namespaces as follows:
Base.php
<?php namespace Helper;
abstract class Base
{
}
Awesome.php
<?php namespace Helper\Awesome;
class Awesome extends Base
{
}
Right now, this says that class Base was not found. I tried to use require_once and/or include to the path of Base.php and they also didn't work. What am I doing wrong?
You are including the file, and that is the right thing to do. But you are also using
namespaces.
the namespace is not a folder, that means the namespace 'Helper' is not a folder but a logical hierarchy. In order to use the class Base in he logical namespace Helper the Awesome class needs to extend the Base class with the full logical path i.e. \Helper\Base.
namespace Helper\Awesome;
class Awesome extends \Helper\Base {
}
or use the use/as keyword instead (like c# using statement) .
namespace Helper\Awesome;
use \Helper\Base as Base;
class Awesome extends Base
{
}
more information can be fount at the php.net site.
here is a direct reference: http://php.net/manual/en/language.namespaces.importing.php

What happens when a namespace and class share a name in PHP?

When using the pseudo namespacing pattern of PEAR and Zend, it is common to come across class heirarchies that look like this:
Zend/
Db.php
Db/
Expr.php
Where DB.php contains a class named Zend_Db and Expr.php contains a class named Zend_Db_Expr. However, when you try to convert the old 5.2 psuedo namespacing into PHP 5.3 namespacing you are presented with a case where a namespace and a class share a name. Since the use operator can import either a namespace or a classname this leads to ambiguity.
Here's an example of an app I'm working on converting:
App/
Core.php
Core/
Autoloader.php
Here the base directory and namespace are App. In the top level of the name space is a Core class:
namespace App;
class Core { }
In the Core directory are various other core classes, some of which use the main Core. Under the pseudo namespacing pattern, this isn't a problem. But in the real namespacing pattern it creates this situation:
namespace App\Core;
use App\Core as Core; // What is this importing? Namespace or class?
class Autoloader {
public function __construct(Core $core) {}
}
Is this defined? What is actually imported here?
Simply both. It is not real import, just a hint for compiler, that every encounter of this alias in class related operations should be expanded to this declaration. In php namespace is just part of class so just think of it like this
$alias = 'Zend_Db';
$zendDB = new $alias;
$aliasExpr = $alias . '_Expr';
$expr = new $aliasExpr;

Using PHP Namespaces

I have been searching websites to try and get a handle on using PHP namespaces, but they all seem quite vague but what they're trying to do is easy to understand!
My question is: I have a file called people.php and in it is defined class called people. If I create another file called managers.php in the same folder can I define a class again called people which extends the original people class but in the namespace of managers, if so do I have to 'include' the original people.php and if so do I put the include after the writing: namespace managers?
Namespaces are a way to group your related classes in packages. What you describe could best be put under a single namespace like
<?php // people.php
namespace com\example\johnslibrary\people;
abstract class People {
}
and then
<?php // manager.php
namespace com\example\johnslibrary\people;
require_once 'path/to/People.php'; // can better use autoloading though
class Manager extends People {
}
because a Manager is a subclass of People, so there is not much of a reason to put them into their own namespace. They are specialized People.
If you want to Managers to be in their own namespace, you can do so, but have to use the fully qualified name when using the extends keyword, e.g.
<?php // manager.php
namespace com\example\johnslibrary\managers;
require_once 'path/to/People.php';
class Manager extends \com\example\johnslibrary\people\People {
}
or import the People class first
<?php // manager.php
namespace com\example\johnslibrary\managers;
use com\example\johnslibrary\People as People;
require_once 'path/to/People.php';
class Manager extends People {
}
See the PHP Manual on Namespaces for extensive documentation.
// people.php
<?php
namespace People;
class People {}
// managers.php
<?php
namespace Managers;
require_once __DIR__.'/people.php';
class People extends \People\People {}
I have old PHP Class and i need to use it in new PHP file as for example:index.php has to use iClass.php. But before using the OLD iClass.php i have to modify it as below, so that i can use it in index.php.
iClass.php:
namespace ic;
class iClass {
public static function callMeFromClass() {
echo 'OK - you have called me!';
exit;
}
}
index.php
namespace inex;
require_once 'iClass.php';
use ic\iClass;
iClass::callMeFromClass();

Categories