Nette\ComponentModel\Container::addComponent PHP Method

    public function addComponent(IComponent $component, $name, $insertBefore = NULL)
    {
        if ($name === NULL) {
            $name = $component->getName();
        }
        if (is_int($name)) {
            $name = (string) $name;
        } elseif (!is_string($name)) {
            throw new Nette\InvalidArgumentException(sprintf('Component name must be integer or string, %s given.', gettype($name)));
        } elseif (!preg_match('#^[a-zA-Z0-9_]+\\z#', $name)) {
            throw new Nette\InvalidArgumentException("Component name must be non-empty alphanumeric string, '{$name}' given.");
        }
        if (isset($this->components[$name])) {
            throw new Nette\InvalidStateException("Component with name '{$name}' already exists.");
        }
        // check circular reference
        $obj = $this;
        do {
            if ($obj === $component) {
                throw new Nette\InvalidStateException("Circular reference detected while adding component '{$name}'.");
            }
            $obj = $obj->getParent();
        } while ($obj !== NULL);
        // user checking
        $this->validateChildComponent($component);
        try {
            if (isset($this->components[$insertBefore])) {
                $tmp = [];
                foreach ($this->components as $k => $v) {
                    if ($k === $insertBefore) {
                        $tmp[$name] = $component;
                    }
                    $tmp[$k] = $v;
                }
                $this->components = $tmp;
            } else {
                $this->components[$name] = $component;
            }
            $component->setParent($this, $name);
        } catch (\Exception $e) {
            unset($this->components[$name]);
            // undo
            throw $e;
        }
        return $this;
    }

 /**
  * @param IComponent $component
  * @param string $name
  * @param IComponent $insertBefore
  * @return Container
  * @throws InvalidArgumentException
  */
 public function addComponent(IComponent $component, $name, $insertBefore = NULL)
 {
     if (!$component instanceof Form) {
         throw new InvalidArgumentException(printf('Form must be instance of Nette\\Forms\\Form, %s given.', get_class($component)));
     }
     return parent::addComponent($component, $name, $insertBefore);
 }