Dependency Injection vs Static

Question

I am learning symfony framework and I am wondering : if I need something like an helper (for example) is it better to make a service (to do a dependancy injection into my controller) or is it better to create a static function. What are the pros and cons of each method.

Thank you in advance :)

Answer 1

This is a very significant question regarding the best way to add reusable libraries that does very specific processes.

The Symfony way is make it a service and register it in the service container.

<?php 

namespace Acme\MainBundle\Services;

class MobileHelper
{
    public function formatMobile($number)
    {
        $ddd = substr($number, 0, 2);
        $prefix_end_index = strlen($number) == 11 ? 5 : 4;
        $prefix = substr($number, 2, $prefix_end_index);
        $suffix = substr($number, -4, 4);

        return sprintf('(%s) %s-%s', $ddd, $prefix, $suffix);
    }

    public function unformatMobile($number)
    {
        $number = preg_replace('/[()-\s]/', '', $number);

        return $number;
    }
}

Then on services.yml

  mobile.helper:
    class: Acme\MainBundle\Services\MobileHelper

Then you can use it in your controller like:

$mobileHelper = $this->get('mobile.helper');
$formattedMobile = $mobileHelper->formatMobile('11999762020');