Advanced — Static Memory

/**
 * Long memory cache. Use this storage to remember results of your calculations, do not store user
 * or non-static data in here (!).
 */
interface MemoryInterface
{
    /**
     * Read data from long memory cache. Must return exacts same value as saved or null. Current
     * convention allows to store serializable (var_export-able) data.
     *
     * @param string $section Non case sensitive.
     * @return string|array|null
     */
    public function loadData(string $section);

    /**
     * Put data to long memory cache. No inner references or closures are allowed. Current
     * convention allows to store serializable (var_export-able) data.
     *
     * @param string       $section Non case sensitive.
     * @param string|array $data
     */
    public function saveData(string $section, $data);
}

abstract class Operation
{
    /**
     * Execute some operation.
     */
    abstract public function perform(mixed $request): void;
}

class OperationService
{
    /**
     * List of operation associated with their class.
     * @var class-string[] 
     */
    protected array $operations = [];

    public function __construct(
        MemoryInterface $memory, 
        ClassesInterface $classes
    ) {
        $this->operations = $memory->loadData('operations');

        if (\is_null($this->operations)) {
            $this->operations = $this->locateOperations($classes); // slow operation
            $memory->saveData('operations', $this->operations);
        }      
    }

    public function run(string $operation, mixed $request): void
    {
        // Perform operation based on $operations property
    }

    /**
     * @return class-string[]
     */
    protected function locateOperations(ClassesInterface $classes): array
    {
        // Generate list of available operations via scanning every available class
    }
}