Create new class instance from string name in an aliased namespace

Question

I\'ve seen questions like this and this, but neither addresses how to create a class instance from a string name if you already have a namespace and the class is in an aliased n

Answer 1

You will simply have to use:

$provider = 'League\OAuth2\Client\Provider\Google';

There is no other solution, class name variables need to contain the fully qualified class name; aliasing doesn't apply to string class names, and introspection can't help you either.

Answer 2

Namespaces are introduced to allow same names in different contexts, so the answer is: no, it is not possible.

You can have a class \League\OAuth2\Client\Provider\Google and another class \League\OAuth1\Client\Provider\Google: in this case, how you can determine what class to instantiate?

Assuming you know that there are only unique class names, you can use this code:

$provider = 'Google';
$found = False;
foreach( get_declared_classes() as $class )
{
    if( preg_match( "~(.*\\\)?($provider)$~", $class ) )
    {
        $found = $class;
        break;
    }
}

if( $found )
{
    $g = new '\\'.$found;
}
else
{
    echo "No '$provider' class found";
}

demo with DateTime class

but this routine is only a simplification of your idea “to use an array to store all the namespaces and class names”, because — even with above code — if you don't know all declared classes, you can obtain unwanted results.