psr-4 changes to working examples do not work - psr-4

Question

I have to achieve that all sources are inclueded like this
$instance = new \d1\d2\d3\app\MyClass();
Where d1\d2\d3\ points to the root directory.
I have read the basics on
https://getcomposer.org/doc/04-schema.md#psr-4
and on
http://www.php-fig.org/psr/psr-4/.
The example on https://laracasts.com/lessons/psr-4-autoloading also works for me.
My problem is: a soon as I change the code below a little bit towards to my needs the class is not found any more. (Yes I issue the command composer update after the changes in composer.json. And yes I updated the composer using self-update).
So this works:
composer.json
"autoload": {
"psr-4": {
"Laracasts\\": "app/Laracasts"
}
}
index.php
require_once 'vendor/autoload.php';
// According to https://laracasts.com/lessons/psr-4-autoloading
$test = new \Laracasts\Repositories\BlogRepository();
$test->hello();
But this does'nt:
composer.json
"autoload": {
"psr-4": {
"d1\\": "app/Laracasts"
}
}
index.php
require_once 'vendor/autoload.php';
// According to https://laracasts.com/lessons/psr-4-autoloading
$test = new \d1\Repositories\BlogRepository();
$test->hello();
What am I doing wrong?
I am using php 5.3.28 with IIS 8.

Answer 1

Solved!
The problem was that Prefix used in composer.json ('d1' in this case) must also be used as the Namespace-Prefix in the class to be included. And this was not the case while I posted the previous post.
For the non-working example above to work the files must look like this in case of 'd1':
app\Laracasts\Repositories\BlogRepository.php
namespace d1\Repositories;
class BlogRepository
{
public function hello(){
echo 'hello from a non-root dir!';
}
}
index.php
require_once 'vendor/autoload.php';
$test = new \d1\Repositories\BlogRepository();
$test->hello();
composer.json
{
"autoload": {
"psr-4": {
"d1\\": "app/Laracasts"
}
}
}
The achieve that d1\d2\d3\ points to the root directory, we have to adjust the prefix in all 3 files mentioned above and move the file with the class to the root directory. Then we have adjust the composer.json like this
"d1\\d2\\d3\\": ""