找不到带有PHP命名空间的Class

Question

I posted some questions previously regarding the use of Namespaces in PHP and from what I got, this example code I have below should be working.

However I am getting errors when I try to use Namespace in PHP like this. Here is the first error when running the code below as is...

Fatal error: Class 'Controller' not found in E:\Controllers\testing.php on line 6

E:\Controller\testing.php File

<?php
use \Controller;

include('testcontroller.php');

$controller = new Controller;
$controller->show();
?>

E:\Controller\testcontroller.php File

<?php
use \Library\Registry;

namespace Controller
{
    class Controller
    {
        public $registry;

        function __construct()
        {
            include('E:\Library\Registry.class.php');
            $this->registry = new Registry;
        }

        function show()
        {
            echo $this->registry;
            echo '<br>Registry was ran inside testcontroller.php<br>';
        }
    }
}
?>

E:\Library\Registry.class.php File

<?php
namespace Library\Registry
{
    class Registry
    {
        function __construct()
        {
            return 'Registry.class.php Constructor was ran';
        }
    }
}
?>

As you can see I tried to make it as simple as possible just to get the Namespace part working. I have tried different variations and cannot seem to figure it out.

Answer 1

Even when using use statement, you need to specify the namespace of the class you are trying to instantiate. There are a lot of examples here: http://www.php.net/manual/en/language.namespaces.importing.php

To understand it better, I will describe to you how it works. In your case, when you do use \Controller, the whole Controller namespace becomes available to you, but not the classes that are in this namespace. So, for example:

<?php
include('testcontroller.php');

use \Controller;

// Desired class is in namespace!
$controller = new Controller\Controller();

// Error, because in current scope there is no such class
$controller = new Controller();

$controller->show();
?>

Another example:

testcontoller.php:

<?php
namespace Some\Path\To\Controller;

class Controller
{
    function __construct()
    {

    }

    function show()
    {
        echo '<br>Was run inside testcontroller.php<br>';
    }
}
?>

testing.php:

<?php
include('testcontroller.php');

use \Some\Path\To\Controller;

// We now can access Controller using only Controller namespace,
// not Some\Path\To\Controller
$controller = new Controller\Controller();

// Error, because, again, in current scope there is no such class
$controller = new Controller();

$controller->show();
?>

If you wish to import exactly the Controller class, you need to do use Controller\Controller - then this class will be accessible in your current scope.