In a Laravel 4 site I have installed a tag cloud library. In this library I wish to edit the return line of a function (I have simplified it here):
return "<span>
{$Variable}
</span>";
and make the $variable a link:
return "<span>
<a href='".Request::url()."/myroute/'>
{$variable}
</a>
</span>";
When I try to run the page I get the error:
Class 'Arg\Tagcloud\Request' not found
I thought that it might mean that the Request class is not visible within the tagcloud class and it has to do with namespaces.
On top of the tagcloud class file there are these lines:
<?php namespace Arg\Tagcloud;
use Illuminate\Support\Facades\Facade;
I have found this page (a list of laravel namespaces)
http://laravel.com/api/index.html
and I have used
use Illuminate\Routing;
or
use Illuminate;
I added them just below the above first two 'use' statements but I get the same error (class not found). Is it a matter of finding the right namespace or something else? Can anyone help? Thanks.
EDIT: I found this way of doing what I wanted without using
Request::url():
return "<span>
<a href='/mysitename/public/myroute/{$variable}'>
{$variable}
</a>
</span>";
Whenever you put your class in a namespace, any other class that you reference in that class assumes that it is also in that same namespace unless you tell it otherwise.
So, since you set your namespace to Arg\Tagcloud when you directly reference Request::url(), PHP thinks that you're telling it to use the Request class inside the Arg\Tagcloud namespace.
There's two solutions to this:
Solution 1
Add a \ in front of Request to tell PHP to use the global namespace, not the Arg\Tagcloud namespace.
e.g., <a href='".\Request::url()."/myroute/'>
Solution 2
use the class.
Just add use Request to the top of your class (under your namespace), this will let PHP know that you want to use this class, but it doesn't belong in the current namespace.
e.g.,
<?php namespace Arg\Tagcloud;
use Request;
When I try to run the page I get the error:
Class 'Arg\Tagcloud\Request' not found
It's because you are using the Request class from Arg\Tagcloud namespace and when you use Request::someMethod() framework things that Request class is under same namespace which is:
Arg\Tagcloud\Request
But, actually, Request class is under, Illuminate\Http namespace and that's why the error is being occurred. To overcome this problem you may use something like this:
\Request::someMethod();
Or you may use following at the top of your class:
use \Request;
You don't need to use use Illuminate\Request; because Request facade class is available in the global namespace (as an alias) which will resolve the Illuminate\Http\Request class. So, you can directly use Request::someMethod() in your code.
Related
I used use the keyword "use" generally above the class definition. Like this:
<?php
namespace suites\plugins\content\agpaypal;
use \Codeception\Util\Fixtures;
use \Codeception\Verify;
use \Codeception\Specify;
class agpaypalTest extends \Codeception\Test\Unit
{
protected $tester;
...
But now I realised, that I have to put the line for the trait Specify into the class definition. Like this:
<?php
namespace suites\plugins\content\agpaypal;
use \Codeception\Util\Fixtures;
use \Codeception\Verify;
class agpaypalTest extends \Codeception\Test\Unit
{
use \Codeception\Specify;
protected $tester;
...
I think it is because the package \Codeception\Specify; is a trait. But I do not understand why I couldn't reuse this trait when I set the line
use \Codeception\Specify;
before the class definition?
I would be happy if someone could point me to a hint or an explanaiton that explains to me where I should use the keyword "use" the best.
In PHP, the keyword use is used in 3 cases:
As class name alias - simply declares short name for a class (must be declared outside of the class definition)
(manual: Using namespaces: Aliasing/Importing )
To add a trait to a class (must be declared inside (at the top) of the class definition)
(manual: Traits)
In anonymous function definition to pass variables inside the function
(manual: Anonymous functions)
You can not import class with use keyword. You have to use include/require statement. Even if you use some 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 same name; you'll find it strange, but when you are working with big MVC structure, this happens. So if you have two classes with same name, put them in different name spaces. 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.
Here refer this
How does the keyword 'use' work
use is basically including a class in the file to use it.
There are two ways to include a class file in another file.
The most general is require or include method. Another method is using composer. Assume this Directory Structure
Project
|
|--- Folder A
| |
| |---UserRegistration.php
|
|---Example
|
|--TestUserRegistration.php
In Folder A there is UserRegistartion.php and you want to use the code in TestUserRegistration.php In UserRegistration.php It can be class, trait or Interface
Method 1.
In TestUserRegisteration.php you can include or require file UserRegistartion.php
and use it
Method 2
Using Composer. In UserRegistration.php you define namespace FolderA; as the first line of code. Then write your code as you do. So Now you want to use this file in TestUserRegistration.php you do
include vendor/autoload.php;
use FolderA\UserRegistration;
Which one is better and why?
Method 2 using composer is the best method. In method 1 wherever you want to include UserRegistration you have to find the relative path to UserRegistration file. So lets assume some day you need to change the directory structure your application will break as the relative path you had provided now it does'nt exist.
But in Method 2 you always use the namespace you provided \ The filename instead of where you want to use. So even you change the directory structure you don't have to got all codes and modify the path. It will work as it was.
To know more study about how to use namespace and composer.
This is a sample code:
sample code
I want to call it in another page:
include 'root of class file';
$r = new ImagineResizer();
I got this error:
Fatal error: Class 'ImagineResizer' not found in C:\WampDeveloper\Websites\example.com\webroot\images.php on line 13
Also call the function:
$r->resize('c:/test1.jpg', 'c:/test2.jpg');
As seen in your sample code the class is located in another namespace :
<?php
namespace Acme\MyBundle\Service;
use Symfony\Component\HttpFoundation\File\File;
use Imagine\Image\ImagineInterface;
use Imagine\Image\BoxInterface;
use Imagine\Image\Point;
use Imagine\Image\Box;
class ImagineResizer {
//-- rest of code
}
To use a class in another namespace you need to point out where the file is :
First include the class (manual or with autoloading)
Then u can create an instance in 2 ways. First way with the use-keyword
use Acme\MyBundle\Service\ImageResizer;
$object = new ImageResizer();
Or point to the class absolute :
$object = new \Acme\MyBundle\Service\ImageResizer();
Hopefully, this will help you out some:
Make sure you include the actual file - not just the folder where it lies.
Make sure that the file you're calling the class from uses the same namespace as your class file. If it doesn't, you have to call the class using the full namespace.
Profit.
The namespaces really had my patience go for a spin when I started using them, but once you're used to it it's not too hard. I would recommend using an autoloader though. It's a bit of a hassle to set up, but once it's done it helps out a bunch.
Namespaces: http://php.net/manual/en/language.namespaces.php
Autoloader: http://php.net/manual/en/function.spl-autoload-register.php
I have a laravel 4.1 application, and I've created a folder in my app folder to store most of the logic.
/app/Acme/Models/
/app/Acme/Repositories/
these are the two main folders.
In my composer.json I have this in the auto load, and done a dump run.
"psr-4" : {
"Acme\\" : "app/Acme"
}
However I am getting, what I think are silly issues. For example my Acme/Models/Task.php has the following
<?php
namespace Acme\Models;
class Task extends \Eloquent {
public function job()
{
return $this->belongsTo('Job');
}
}
however when I run this, I get an error
Fatal error: Class 'Task' not found in vendor/laravel/framework/src/Illuminate/Database/Eloquent/Model.php on line 780
In my Job.php I have the same namespace at the top of the file....
Must I manually import/use object which are in the same name space?
use Acme/Models/Job as Job; ? it seems like such a duplicate...
And in my Repositories folder when I set a namespace of namespace Acme/Repositories;, must I use items like
use Acme\Models\Job as Job;
I is, a bit lost!
Namespaces are relative so you do not need to add use to directly reference classes within the same namespace.
The error you are getting is because you need to fully qualify relationships to namespaced models so eloquent knows where to find them eg
$this->belongsTo('\Acme\Models\Jobs');
In the case of your repository namespace, you will need to add a use statement in your file as you suggested, or reference the fully qualified namespace eg new \Acme\Models\Job();
On a side note, I know PHPStorm (and I'm sure other IDEs) will inject the namespaces for you which is super useful and saves you having to write use or the full namespace out every time you reference a class - worth checking out.
Edit: Sorry, I didn't read the question properly first time around - updated my answer.
I'm trying to rewrite an OO PHP site (that loosely follows an MVC structure) so it uses namespaces - and want to follow PSR-0.
In the current site I have a class (called APP) which is full of static methods that I call all over the place to handle things such as getting config data eg; APP::get_config('key').
Obviously with namespacing, I would need to call \TheNameSpace\App::get_config('key'). I use this class frequently, so want to avoid having to prefix the namespace every time I use it. I do call methods in it from within other classes, which would usually be under a sub-namespace - so changing the namespace at the top of the file won't really work.
So, I guess my question is, what is the easiest way to have a 'global' class with methods that I can call anywhere without having to prefix with the namespace each time?
namespace Foo;
use Bar;
Then you do not have to do \Bar\fn
So in your case:
namspace Foo;
use TheNameSpace\App;
App::get_config('blah')
Read the section in the php manual on using/aliasing namespaces.
http://www.php.net/manual/en/language.namespaces.importing.php
You can exclude the namespace by using "use". You can name it whatever you want.
use TheNamespace\App as App //You can name it anything here
App:config('key');
At top of your scripts add
use TheNameSpace\App as MyApp
for example. You can then use it like
app = new MyApp();
in your scripts. Of course you needn't to use an alias here. Just
use TheNameSpace\App
app = new App();
will work, too.
A global class that's implementing this one is bad style and you shouldn't do it like this:
class MyApp extends TheNameSpace\App { }
....
myApp = new MyApp();
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.