<?php
namespace PortailTestControllerConnexion;

use MagentoFrameworkAppActionAction;
use MagentoFrameworkAppActionContext;
use MagentoFrameworkAppObjectManager;
use MagentoFrameworkViewResultPageFactory;
use MagentoStoreModelStoreManagerInterface;

class Form extends Action
{
    protected $_pageFactory;
    protected $storeManager;

    public function __construct(Context $context,  StoreManagerInterface $storeManager, PageFactory $pageFactory)
    {
        $this->storeManager = $storeManager;
        $this->_pageFactory = $pageFactory;
        return parent::__construct($context);
    }
...
    }