I`m use namespace in my project. But namespace not works.
file index.php
use \Folder\Aa;
Aa::test();
$test = new Aa();
file Folder/Aa.php
namespace Folder;
class Aa
{
static function test()
{
$a = 3;
echo $a;
}
}
Write me Fatal error: Class 'Folder\Aa' not found in /home/ademidko/www/first.local/index.php
I`m changes namespace in Аа.php, write "use \Folder" and other -> but not works
PHP does not load classes dynamically by itself. In order to you to be able to use your class your code have to look like this:
require_once('Folder/Aa.php');
use \Folder\Aa;
Aa::test();
$test = new Aa();
There are many possible ways how to make this work without manually writing require or require_once. One of them is to use composer's autoloading functionality (details can be found here: https://getcomposer.org/doc/04-schema.md#psr-4).
You can also consider writing your own autoloader (more details here: http://php.net/manual/en/function.spl-autoload-register.php)
Related
I'm using laravel 5.6, and in my controller I have
use RecursiveIteratorIterator;
and the error I'm getting is
Class 'App\Http\Controllers\RecursiveArrayIterator' not found
So I'm being a little simplistic about it. Obviously RecursiveIteratorIterator is not a laravel function, but rather a core php function. But after reading this post https://laraveldaily.com/how-to-use-external-classes-and-php-files-in-laravel-controller/ I'm still no clearer on where to find it, or how to reference it properly.
I suppose I was expecting that all "native" php functions would just be available?
Help?
You want to put a backslash in front (No need to put use ... at the top), to specify a root/global class:
\RecursiveIteratorIterator;
For more information, refer to the PHP documentation here:
Example #3 Accessing internal classes in namespaces
<?php
namespace foo;
$a = new \stdClass;
function test(\ArrayObject $typehintexample = null) {}
$a = \DirectoryIterator::CURRENT_AS_FILEINFO;
// extending an internal or global class
class MyException extends \Exception {}
?>
Just to be mention, it looks like you are only importing
use \RecursiveIteratorIterator;
and also calling RecursiveArrayIterator somewhere in the code. try importing both.
use \RecursiveIteratorIterator;
use \RecursiveArrayIterator;
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 am working on the AWS documentation which uses Guzzle framework. I have to deal with namespaces here and I am not able to get it working. I went through the docs and examples and understood that we can have packages for projects using namespaces.
I went ahead and tried a simple example, but unsuccessful. Here's the example: this is the index.php:
use My\Full\Classname as Another; //Also tried use My\Full\Classname
$obj = new Another; //with $obj = new Classname;
echo $obj->add();
I have Classname.php in the directory structure like this My->Full->Classname.php:
<?php
class Classname{
public static function add(){
return 2+2;
}
}
?>
I am trying to call the function in index.php but getting error:
Fatal error: Class 'Another' not found in C:\wamp\www\guzzleEx\index.php on line 19
which is the line where I instantiate the Classname object $obj = new Another;
What is the mistake i am making? Is there any INI that needs to be updated or any other config issue? How can I make the code working? If you use the normal include for Classname.php it works fine.
Namespaces need to be explicitly declared, they do not come from a certain directory structure.
So if you do not have a line that reads namespace My\Full; in front of your class Classname, then your class is not in any namespace, but in the root namespace.
Thus you cannot use it as \My\Full\Classname, but \Classname or even Classname directly.
Does PHP have some sort of using namespace of C++? (So you don't have to write any namespace before your calls)
I have defined a function within:
namespace \Project\Library {
function hello() {
}
}
Another file.php:
use \Project\Library;
hello(); //> Error: Call to undefined function hello()
PS.
I know I could use use \Project\Library as L;
And then do L\hello();
I want to avoid L\ too.
Edit
I answer myself: you cannot do it. And that sucks imo (this is the first thing I don't like of PHP).
Edit2
To be clear: If hello() was a class I could call it directly using use. The problem it is that is a simple function so I have to write its namespace. This is a little mindfucking of PHP.
Maybe we can consider this a bug and open a ticket?
Since PHP 5.3.0 it supports syntax use ... as:
use My\Full\Classname as Another
Also guessing from manual using use directly (without as Another) is not possible (it's not mentioned in manual).
You may be able to use some hack like class factory or workaround via autoloader but simple and direct answer is "it's not possible". :(
Even if PHP has namespaces and can declare functions directly outside a class, I would strongly suggest that you, at least, use static class methods. Then you don't have to hack things around and will use namespaces as they were designed to work; with classes.
Here is a working example :
hello.php
<?php
namespace Project\B;
class HelloClass {
static function hello() {
echo "Hello from hello.php!";
}
}
a.php
<?php
namespace Project\A;
require('hello.php'); // still have to require the file, unless you have an autoloader
use \Project\B\HelloClass; // import this class from this namespace
\Project\B\HelloClass::hello(); // calling it this way render the 'use' keyword obsolete
HelloClass::hello(); // or use it as it is declared
** Note **: use foo as bar; let's you rename the class! For example :
use \Project\B\HelloClass as Foo; // import this class from this namespace as Foo
Foo::hello(); // calling it this way using the 'use' keyword and alias
** Update **
Interestingly, you can do this :
c.php
namespace Project\C;
function test() {
echo "Hello from test!\n";
}
a.php
use \Project\C; // import namespace only
use \Project\C as Bar; // or rename it into a different local one
C\test(); // works
Bar\test(); // works too!
So, just write use Project\Library as L; and call L\hello();. I think it's your best option here.
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.