Manager.php

<?php
use Illuminate\Support\Collection;
/**
 * @method self registerCustomer(Closure $query, Closure $filter)
 * @method self registerAccounts(Closure $query, Closure $filter)
 */
class Manager
{
    // Allowed virtual methods.
    private array $methods = [
        'customer',
        'accounts'
    ];

    private Collection $callbacks;

    public function __construct()
    {
        $this->callbacks = new Collection;
    }

    public function __call($method, $args)
    {
        $type = (string)str($method)->remove('register')->lower();

        //Allow virtual public methods to be called.
        if (!in_array($type, $this->methods)) {
            throw new BadMethodCallException();
        }

        $this->callVirtualMethod($type, $args);
        return $this;
    }

    protected function callVirtualMethod($type, $args): void
    {
        $this->callbacks->put($type, [
            $type => [
                'query'  => $args[0],
                'filter' => $args[1],
            ]
        ]);
    }

    public function getCallbacks(string $type): stdClass
    {
        if(!$this->callbacks->has($type)){
            throw new InvalidArgumentException(
                'Required callback must be registered: '. (string)str($type)->title()->prepend('register'))
            );
        }
        return (object) $this->callbacks->get($type);
    }
}

dd((new Manager)->registerCustomer(fn()=>true, fn()=>false)->getCallbacks('customer'));