core-bundle/src/Resources/contao/modules/ModuleMaintenance.php
protected function compile()
	{
		System::loadLanguageFile('tl_maintenance');

		$this->Template->content = '';
		$this->Template->href = $this->getReferer(true);
		$this->Template->title = StringUtil::specialchars($GLOBALS['TL_LANG']['MSC']['backBTTitle']);
		$this->Template->button = $GLOBALS['TL_LANG']['MSC']['backBT'];

		foreach ($GLOBALS['TL_MAINTENANCE'] as $callback)
		{
			$this->import($callback);

			if (!$this->$callback instanceof \executable)
			{
				throw new \Exception("$callback is not an executable class");
			}

			$buffer = $this->$callback->run();

			if ($this->$callback->isActive())
			{
				$this->Template->content = $buffer;
				break;
			}
			else
			{
				$this->Template->content .= $buffer;
			}
		}
	}
protected function compile()
	{
		System::loadLanguageFile('tl_maintenance');

		$this->Template->content = '';
		$this->Template->href = $this->getReferer(true);
		$this->Template->title = StringUtil::specialchars($GLOBALS['TL_LANG']['MSC']['backBTTitle']);
		$this->Template->button = $GLOBALS['TL_LANG']['MSC']['backBT'];

		foreach ($GLOBALS['TL_MAINTENANCE'] as $callback)
		{
			$this->import($callback);

			if (!$this->$callback instanceof \executable)
			{
				throw new \Exception("$callback is not an executable class");
			}

			$buffer = $this->$callback->run();

			if ($this->$callback->isActive())
			{
				$this->Template->content = $buffer;
				break;
			}
			else
			{
				$this->Template->content .= $buffer;
			}
		}
	}
Generate the module

@throws \Exception