Logger/Handler/BaseHandlerFactory.php
protected function initHandler(HandlerInterface $handler)
    {
        if ($this->formatter != null) {
            $handler->setFormatter($this->formatter);
        }

        foreach ($this->processors as $processor) {
            $handler->pushProcessor($processor);
        }

        return $handler;
    }
protected function initHandler(HandlerInterface $handler)
    {
        if ($this->formatter != null) {
            $handler->setFormatter($this->formatter);
        }

        foreach ($this->processors as $processor) {
            $handler->pushProcessor($processor);
        }

        return $handler;
    }
Sets formatter and processors.

@param HandlerInterface $handler
@return HandlerInterface