I have two classes in the same folder in own files. But when I am trying to extends one to another it is giving namespace and class not found error.
Info: It is the first time I am extending class using namespace. Also nested namespace is new to me. DB\CRUD So may be I am doing
completely wrong with namespace.
Error message:
Fatal error: Class 'DB\AT_Database' not found in /var/www/...
DB class
File: AT_Database.php
namespace DB;
class AT_Database
{
...
}
CRUD class
File: AT_CRUD.php
namespace DB\CRUD;
use DB\AT_Database;
class AT_CRUD extends AT_Database
{
public function __construct()
{
}
}
This may be silly mistake or may be I have overlooked it (which I should not as a programmer) and that is loading sequence of the class.
May be it's not worth to have as an answer but just adding so by chance in future it can help to someone who make such mistake.
As I mentioned in one of my comment, I am using glob to auto load all class files to include.
foreach ( glob( $this->classes_dir . "/*.php" ) as $class ) {
include_once $class;
}
Now my file names are AT_CRUD.php and AT_Database.php. Here I realized that php loads files in alphabetical order. So when I extends AT_Database class into AT_CRUD its never found.
This is just because php loads AT_CRUD first than AT_Database so either I have to instantiate the class into or to use something like dependancy injection as #prehfeldt mention in his comment.
Related
I created a class at Controller folder of Cake project like this:
<?php
class Hi
{
function __construct(){ }
public function hi()
{
echo "hi!";
exit;
}
}
Then in a controller, I tried to include it:
<?php
namespace App\Controller;
use App\Controller\AppController;
include_once "Hi.php";
class MyController extends AppController
{
public function sayHi()
{
$a = new Hi();
$a.hi();
}
}
Here is the error I'm having:
Fatal error: Cannot declare class Hi, because the name is already in use in path\api\src\Controller\Hi.php on line 2
What's going on?
MyController.php and Hi.php are in the same folder. I'm using PHP 7.
Including a file won't make the classes in that file part of the current namespace, as namespaces are a per-file functionality.
http://php.net/...namespaces.importing.php#language.namespaces.importing.scope
Your Hi class will be declared in the global namespace, and your new Hi() will cause PHP to look for it in the current namespace, ie it will look for App\Controller\Hi, which doesn't exist, hence the composer autoloader kicks in, and will map this via a PSR-4 namespace prefix match to src/Controller/Hi.php, which will include the file again, and that's when it happens.
http://www.php-fig.org/psr/psr-4/
Long story short, while using new \Hi() would fix this, you better not include class files manually, or declare them in paths where they do not belong. Instead declare your files and classes in a proper autoloading compatible fashion, that is for example with a proper namespace in a path that matches that namespace, like
namespace App\Utils;
class Hi {
// ...
}
in
src/Utils/Hi.php
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;
PHP 5.6
This code:
<?php
namespace Database
{
abstract class Model
{
}
}
namespace Models
{
use Database\Model as DbModel;
class Model extends DbModel
{
}
}
namespace Models
{
use Database\Model;
class Brand extends Model
{
}
}
namespace
{
$m = new \Models\Model();
}
causes an error:
"Fatal error: Cannot use Database\Model as Model because the name is already in use in D:\OpenServer\domains\localhost\index.php on line 23".
This code:
<?php
namespace Models
{
use Database\Model as DbModel;
class Model extends DbModel
{
}
}
namespace Models
{
use Database\Model;
class Brand extends Model
{
}
}
namespace Database
{
abstract class Model
{
}
}
namespace
{
$m = new \Models\Model();
}
has no errors.
Why is this happening? Because the code has not been changed.
The ordering of your namespace clauses makes the difference here; in the first example, the Database namespace clause is declared before the clause that defines the class Models\Model.
A similar example of that difference can be found in the documentation:
(...) However, the next example causes a fatal error on name conflict because MyClass is defined in the same file as the use statement.
Separate files or same file here is simulated by moving the Database namespace below or above, respectively.
That said, the documentation also states:
It is strongly discouraged as a coding practice to combine multiple namespaces into the same file. The primary use case is to combine multiple PHP scripts into the same file.
Update
Interestingly, this problem is what Drupal 8 developers recently found out as well, but according to this bug report it has been reported more than two years ago.
A pull request has been submitted to address this issue for the next major version (it may be back ported to 5.x as well).
After few tests: PHP file with few namespaces behave difficult to understand, try to do not use more then one namespace in one file.
(It's because of linking to not existing classes while parsing [of one file!] that change order of PHP parsing, C++ things [pointers] - I can't explain that.)
As PHP doc says:
"It is strongly discouraged as a coding practice to combine multiple namespaces into the same file."
More about tests I did and documentation we studied to find it out:
https://chat.stackoverflow.com/rooms/71776/discussion-between-axiac-and-jack
Im trying to figure out how namespaces works in PHP, but havent really been lucky
Hope somebody could tell me what Im doing wrong here :)
code
require_once 'Vatcode.php';
$Vatcode = new \resource\Vatcode();
Vatcode.php
namespace resource;
require_once Ini::get('path/class').'/Resource.php';
class Vatcode extends Resource {
public function __construct(){
echo 'works!';
}
}
Rescource.php
namespace resource;
class Resource {
}
error
Fatal error: Class 'resource\Ini' not found in Vatcode.php
it's just a problem of namespace.
Your class Vatcode is in namesapce ressource. If, in the file of VatCode declaration you use nameofclas::... or new nameofclass() it will try to get the class in namespace ressource.
If you want to use the class Ini inside your document you have two solutions :
first give the full qualified name :
require \namespace\of\ini\Ini::get('path/class').'/Resource.php';
second using the "use" keyworld before using the get method :
use \namespace\of\ini\Ini;
require_once Ini::get('path/class').'/Resource.php';
In any case, if Ini is in "no namespace" (global namespace is the accurate word) you just has to use the solutions I gave you but only with \Ini instead of \namespace\of\ini\Ini
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();