Extend a class without namespace

Have you tried with require and require_once PHP expressions?

Maybe, something like this:

require_once("YourClass.php"); // Here with the path to YourClass.php
class AnotherClass extends YourClass 
{
   ...
}

@pixelairport The class will exist in the “global” namespace, so you either need to import it as is, or prepend a backslash to the class name when extending it:

use NF_Abstracts_Action;

final class GoSomewhere extends NF_Abstracts_Action
{
    //
}

Or:

final class GoSomewhere extends \NF_Abstracts_Action
{
    //
}

Also the PHP manual has a lot on namespace:

https://www.php.net/manual/en/language.namespaces.faq.php

Your question it's similar to example number 3.

And https://www.php.net/manual/en/language.namespaces.rationale.php

Thx all for help. I already tried everything of this... i also checked if the class is there:

if(class_exists('NF_Abstracts_Action')) {
    die('hello');
}
// => Outputs hello

... and it is loaded. But when I do

 final class MultiMailjet extends NF_Abstracts_Action

i got: Fatal error: Uncaught Error: Class 'MyPlugin\Actions\NF_Abstracts_Action' not found in.

When I do

 final class MultiMailjet extends \NF_Abstracts_Action

i got: Warning: require_once(Actions/Ninja_Forms.php): failed to open stream: No such file or directory

...

I think the problem is, that autoloading tries to load it, even the class already exists. I got an error when doing the following code, that class "Myplugin\Actions\NF_Abstracts_Action" is not found even it seems class is loaded.:

if(class_exists('NF_Abstracts_Action')) {
    $test = new NF_Abstracts_Action();
}

I have no idea what else can i test/try now.

Have you tried a:

composer dumpautoload

Otherwise you may have to require the class.

Edit: Also check Wordpress forum.

Thx. I checke this. Still dont work. The autoloader is setup in my new wordpress plugin and i extend a plugin which dont use namespaces. Is there a way to do something like alias in laravel config? ... but alias also use namespaces. I want to extend a class which has no namespace.

You will probably have to use @thinway answer, but I usually just require. If you use that, you need whole path.

That is what i did first and I use the whole path. Without the path there would be another error. The file is loaded.

require_once (WP_PLUGIN_DIR.'/ninja-forms/includes/Abstracts/Action.php');
$myclass = new NF_Abstracts_Action();

This throws an error. The Actions.php is really a abstract class: "abstract class NF_Abstracts_Action"

Autloader seems to try load the class again. Could this be the error?

I have this to autoload my plugin files:

function plugin_mailjet_spl_autoloading($class_name)
{
    if (false !== strpos($class_name, 'MyPlugin')) {
        $class_name = str_replace('MyPlugin\', "", $class_name);
        $class_name = str_replace('\', DIRECTORY_SEPARATOR, $class_name);
        require_once($class_name . ".php");
    }
}
spl_autoload_register('plugin_mailjet_spl_autoloading');

Don't try to initiate it, just extend it. See https://medium.com/oceanize-geeks/implementation-of-php-abstract-class-interfaces-a271d57cd8a6

What do you mean with "initiate"? In wordpress there is no autloading. Also most plugins dont have autoloading. So i decided to use it for my plugin. And my plugin tries to load a class from another which dont have autoloading. But my plugin is in a autoloading context. So also when I extend the abstract class, php tries to autoload it again and looks at my autoloading.

... im a step closer... i have to do the thing like @martinbean said... sorry... I have also to load other classes, because abstract class loads other, which sounds familiar. That is why i everytime thought it does not work. But extends works and throws an error because of similar class names which are required. Thx everyone for help.