I'm trying to use this library: https://github.com/duzun/hQuery.php
My project is ordonated like this:
BetCompare
Application
Teams
file_using_the_library.php
hQueryLib
hquery.php
So here is how I'm using it in my php file:
namespace BetCompare\Application\Teams;
use BetCompare\Application\Teams\hQueryLib\hquery;
hQuery::$cache_path = "/path/to/cache";
This returns an error Class not found. I've tried this after a few researches on the matter:
namespace BetCompare\Application\Teams;
use BetCompare\Application\Teams\hQueryLib\hquery;
include_once 'hQueryLib/hquery.php';
hQuery::$cache_path = "/path/to/cache";
Then the error is the following: Cannot declare class hQuery_Context, because the name is already in use. I don't understand, the second error makes it look like the use was enough and loaded the class. But I can't use it... What am I doing wrong?
I've also tried only using include_once but it doesn't work.
Either like this (with namespace duzun\hQuery):
<?php
namespace BetCompare\Application\Teams;
use duzun\hQuery;
include_once 'hQueryLib/hquery.php';
hQuery::$cache_path = "/path/to/cache";
or like this, without the namespace:
<?php
namespace BetCompare\Application\Teams;
include_once 'hQueryLib/hquery.php';
\hQuery::$cache_path = "/path/to/cache";
Your code can not work, because if you write
use BetCompare\Application\Teams\hQueryLib\hQuery;
you are practically assuming, that the hQuery class has the namespace definition
namespace BetCompare\Application\Teams\hQueryLib;
which it does not have (beeing a third-party class).
The part with the duzun\hQuery is defined in the last lines of the hQuery.php file and described in the docus.
I got a simple question for you hopefully. Can it be possible that I just initialize the namespace for a class once in my "main file" and all other objects or classes got the same reference of it ?
For example Index.php:
require_once 'init.php';
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;
and now I got a class not in the same file with this kind of code. Controller.php:
function programmAction($id) {
$programm = $this->model->getProgrammById($id);
$html = $this->renderTemplate($this->tempProgramm,['programm' => $programm]);
return new Response($html);
}
Normally when I don't add the use lines as well to this file I would get an error message that the class Response was not found.
Only if you include all other classes in the same file. Refer to this note from the manual:
Note:
Importing rules are per file basis, meaning included files will NOT inherit the parent file's importing rules.
Please don't include all of your classes in one file.
It may seem like a pain to retype the use statements in each and every class file, but really it will help you when you go back and refer to that file later. Right at the top is a list of classes that your class depends on, and could be helpful information during a refactoring or code reorganization.
here i have a Crypt.php file . its a class have two function, and stored it in "\backend\components" folder. i call this file(class) in my controller using this code
$security = new \backend\components\Crypt();
at run time i am getting this error:
"Unknown Class – yii\base\UnknownClassException
Unable to find 'backend\components\Crypt' in file: E:\xampp\htdocs\pope-Admin/backend/components/Crypt.php. Namespace missing?"
in this path half of them have slash(/) and half of the part have back slash() how to solve it?
In your Crypt class file, include namespace declaration like so:
<?php
namespace backend\components;
class Crypt {
...
}
?>
Use the include(_once) or require(_once) keywords to include the Crypt.php file, then just use new Crypt(). You cant define an instance of a class like that, you have to include the filw containg the class code and only then you can use the new keyword.
I just wanna use a namespace in another file, to use the class in it, but im too retarded to do this...
first file:
namespace fun;
use fun\kjr\trouble;
$trouble = new trouble('http://someURL');
second file:
namespace fun\kjr;
class trouble { ... }
This is the error i get:
Error: Fatal error: Class 'fun\kjr\trouble' not found in D:\wamp\www\fun\index.php on line 8
Where did I declare a wrong namespace? Oo
Greetings
I had to include my class aswell.
use namespace
only makes the class available in the actual context.
It does NOT include it, so you can cause it.
use
include_once('your.file')
to do that!
Thanks #Michael Berkowski for helping.
The problem (from what I can see) is you haven't specified an autoloader (e.g. with spl_autoload_register()) or haven't included the file in your code. The use statement will only find a class for you if you have an autoloader in place, otherwise you must include your code ahead of time with include/include_once or require/require once.
I would start with making an autoloader and registering it and then it may be wise to map your namespaces to directory structure as specified by PSR-0.
I have a file with a class Resp. The path is:
C:\xampp\htdocs\One\Classes\Resp.php
And I have an index.php file in this directory:
C:\xampp\htdocs\Two\Http\index.php
In this index.php file I want to instantiate a class Resp.
$a = new Resp();
I know I can use require or include keywords to include the file with a class:
require("One\Classes\Resp.php"); // I've set the include_path correctly already ";C:\xampp\htdocs". It works.
$a = new Resp();
But I want to import classes without using require or include. I'm trying to understand how use keyword works. I tried theses steps but nothing works:
use One\Classes\Resp;
use xampp\htdocs\One\Classes\Resp;
use htdocs\One\Classes\Resp;
use One\Classes;
use htdocs\One\Classes; /* nothing works */
$a = new Resp();
It says:
Fatal error: Class 'One\Classes\Resp' not found in C:\xampp\htdocs\Two\Http\index.php
How does the keyword use work? Can I use it to import classes?
No, you can not import a class with the use keyword. You have to use include/require statement. Even if you use a PHP auto loader, still autoloader will have to use either include or require internally.
The Purpose of use keyword:
Consider a case where you have two classes with the same name; you'll find it strange, but when you are working with a big MVC structure, it happens. So if you have two classes with the same name, put them in different namespaces. Now consider when your auto loader is loading both classes (does by require), and you are about to use object of class. In this case, the compiler will get confused which class object to load among two. To help the compiler make a decision, you can use the use statement so that it can make a decision which one is going to be used on.
Nowadays major frameworks do use include or require via composer and psr
1) composer
2) PSR-4 autoloader
Going through them may help you further.
You can also use an alias to address an exact class. Suppose you've got two classes with the same name, say Mailer with two different namespaces:
namespace SMTP;
class Mailer{}
and
namespace Mailgun;
class Mailer{}
And if you want to use both Mailer classes at the same time then you can use an alias.
use SMTP\Mailer as SMTPMailer;
use Mailgun\Mailer as MailgunMailer;
Later in your code if you want to access those class objects then you can do the following:
$smtp_mailer = new SMTPMailer;
$mailgun_mailer = new MailgunMailer;
It will reference the original class.
Some may get confused that then of there are not Similar class names then there is no use of use keyword. Well, you can use __autoload($class) function which will be called automatically when use statement gets executed with the class to be used as an argument and this can help you to load the class at run-time on the fly as and when needed.
Refer this answer to know more about class autoloader.
use doesn't include anything. It just imports the specified namespace (or class) to the current scope
If you want the classes to be autoloaded - read about autoloading
Don’t overthink what a Namespace is.
Namespace is basically just a Class prefix (like directory in Operating System) to ensure the Class path uniqueness.
Also just to make things clear, the use statement is not doing anything only aliasing your Namespaces so you can use shortcuts or include Classes with the same name but different Namespace in the same file.
E.g:
// You can do this at the top of your Class
use Symfony\Component\Debug\Debug;
if ($_SERVER['APP_DEBUG']) {
// So you can utilize the Debug class it in an elegant way
Debug::enable();
// Instead of this ugly one
// \Symfony\Component\Debug\Debug::enable();
}
If you want to know how PHP Namespaces and autoloading (the old way as well as the new way with Composer) works, you can read the blog post I just wrote on this topic: https://enterprise-level-php.com/2017/12/25/the-magic-behind-autoloading-php-files-using-composer.html
You'll have to include/require the class anyway, otherwise PHP won't know about the namespace.
You don't necessary have to do it in the same file though. You can do it in a bootstrap file for example. (or use an autoloader, but that's not the topic actually)
The issue is most likely you will need to use an auto loader that will take the name of the class (break by '\' in this case) and map it to a directory structure.
You can check out this article on the autoloading functionality of PHP. There are many implementations of this type of functionality in frameworks already.
I've actually implemented one before. Here's a link.
I agree with Green, Symfony needs namespace, so why not use them ?
This is how an example controller class starts:
namespace Acme\DemoBundle\Controller;
use Symfony\Bundle\FrameworkBundle\Controller\Controller;
class WelcomeController extends Controller { ... }
Can I use it to import classes?
You can't do it like that besides the examples above. You can also use the keyword use inside classes to import traits, like this:
trait Stuff {
private $baz = 'baz';
public function bar() {
return $this->baz;
}
}
class Cls {
use Stuff; // import traits like this
}
$foo = new Cls;
echo $foo->bar(); // spits out 'baz'
The use keyword is for aliasing in PHP and it does not import the classes. This really helps
1) When you have classes with same name in different namespaces
2) Avoid using really long class name over and over again.
Using the keyword "use" is for shortening namespace literals. You can use both with aliasing and without it. Without aliasing you must use last part of full namespace.
<?php
use foo\bar\lastPart;
$obj=new lastPart\AnyClass(); //If there's not the line above, a fatal error will be encountered.
?>
Namespace is use to define the path to a specific file containing a class e.g.
namespace album/className;
class className{
//enter class properties and methods here
}
You can then include this specific class into another php file by using the keyword "use" like this:
use album/className;
class album extends classname {
//enter class properties and methods
}
NOTE: Do not use the path to the file containing the class to be implements, extends of use to instantiate an object but only use the namespace.