example.php

<?php

interface Task
{
    /**
     * @return bool
     */
    public function shouldLog();
}

class EmailTask implements Task
{
    public function shouldLog()
    {
        return false;
    }
}

$handler->handle(new EmailTask()); // no logging

// then you want to debug a problem. With that classes structure, you could...

$handler->handle(new class extends EmailTask {
    public function shouldLog()
    {
        return true;
    }
});