Magento2 - how do I call a function in another class? - magento2

Question

I'm creating an observer and I'm trying to connect it to saving a new product. If the product is new I'm trying to run a code, if not - skip.
I made an observer before save in creating a new product and after that I want to run the same code as shared catalog -> shared catalogs -> default -> set pricing and structure -> and just save without changing anything.
This is my code:
NewProductReindexer/etc/adminhtml/events.xml
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Event/etc/events.xsd">
<event name="catalog_product_save_before">
<observer name="Company_module_event_after_observer" instance="Company\NewProductReindexer\Observer\NewProductObserver"/>
</event>
Observer/NewProductObserver.php
class NewProductObserver implements ObserverInterface
{
public function __construct()
{
}
public function execute(Observer $observer)
{
$isProductNew = $product->isObjectNew();
if($isProductNew == true){
//new product
}else{
relax();
}
}
}

Answer 1

The two ways to call you a block class method in the custom module class
using constructor dependency like that
public function __construct(Namespace\ModuleName\Helper\Data $helper)
{
$this->helper = $helper;
}
public function MyFunction()
{ $this->helper->HelperDemo();
}
using method dependency public function execute(Namespace\ModuleName\Helper\Data $helper) { $helper->HelperDemo(); }
For more detail visit the below link https://devdocs.magento.com/guides/v2.3/extension-dev-guide/depend-inj.html