Plugins

Plugins let you modify the input or output of any public method on any class — without replacing the class itself. They’re the fine-grained counterpart to Preferences.

Plugin Types

Marko supports two plugin types:

Type	When It Runs	What It Can Do
Before	Before the original method	Modify input arguments
After	After the original method	Modify the return value

Creating a Plugin

A plugin is a plain PHP class with methods that follow a naming convention:

<?php

declare(strict_types=1);

namespace App\MyApp\Plugin;

use Marko\Blog\Repository\PostRepository;

class PostRepositoryPlugin
{
    /**
     * Modify arguments before getPost() is called.
     */
    public function beforeGetPost(PostRepository $subject, int $id): array
    {
        // Log or transform the input
        return [$id]; // Return modified arguments as array
    }

    /**
     * Modify the return value after getPost() completes.
     */
    public function afterGetPost(PostRepository $subject, array $result): array
    {
        // Add extra data to the result
        $result['retrieved_at'] = time();

        return $result;
    }
}

Method Naming

beforeMethodName — runs before methodName
afterMethodName — runs after methodName

The first parameter is always $subject (the original object). For before plugins, remaining parameters match the original method’s signature. Return an array of the (possibly modified) arguments.

For after plugins, the second parameter is the result from the original method. Return the (possibly modified) result.

Registering Plugins

Plugins are registered in module.php:

<?php

declare(strict_types=1);

use App\MyApp\Plugin\PostRepositoryPlugin;
use Marko\Blog\Repository\PostRepository;

return [
    'plugins' => [
        PostRepository::class => [
            PostRepositoryPlugin::class,
        ],
    ],
];

Plugin Execution Order

When multiple plugins target the same method:

All before plugins run (in module priority order)
The original method runs
All after plugins run (in module priority order)

When to Use Plugins

Plugins are ideal for cross-cutting concerns:

Adding logging to specific methods
Transforming data before it’s saved
Adding validation before an action
Enriching return values with additional data

If you need to replace the entire behavior, use a Preference instead.

Next Steps

Events & Observers — for decoupled, reactive behavior
Preferences — for full implementation replacement
Core Package — API reference for the plugin system