Nette\Forms\Form::attached PHP Method

    protected function attached($obj)
    {
        if ($obj instanceof self) {
            throw new Nette\InvalidStateException('Nested forms are forbidden.');
        }
    }

	/**
	 * This method will be called when the component (or component's parent)
	 * becomes attached to a monitored object. Do not call this method yourself.
	 * @param  Nette\ComponentModel\IComponent
	 * @return void
	 */
	protected function attached($presenter)
	{
		if ($presenter instanceof Presenter) {
			$name = $this->lookupPath('Nette\Application\UI\Presenter');

			if (!isset($this->getElementPrototype()->id)) {
				$this->getElementPrototype()->id = 'frm-' . $name;
			}

			if (iterator_count($this->getControls()) && $this->isSubmitted()) {
				foreach ($this->getControls() as $control) {
					if (!$control->isDisabled()) {
						$control->loadHttpData();
					}
				}
			}

			if (!$this->getAction()) {
				$this->setAction(new Link($presenter, 'this', array()));
				$signal = new Nette\Forms\Controls\HiddenField($name . self::NAME_SEPARATOR . 'submit');
				$signal->setOmitted()->setHtmlId(FALSE);
				$this[Presenter::SIGNAL_KEY] = $signal;
			}
		}
		parent::attached($presenter);
	}