core-bundle/src/Resources/contao/library/Contao/Widget.php
public function addAttributes($arrAttributes)
	{
		if (!\is_array($arrAttributes))
		{
			return;
		}

		foreach ($arrAttributes as $k=>$v)
		{
			$this->$k = $v;
		}
	}
public function addAttributes($arrAttributes)
	{
		if (!\is_array($arrAttributes))
		{
			return;
		}

		foreach ($arrAttributes as $k=>$v)
		{
			$this->$k = $v;
		}
	}
Take an associative array and add it to the object's attributes

@param array $arrAttributes An array of attributes