Alternative for .inc files

Question

I was wondering what is the correct alternative of .inc files in Drupal 8? That is to say, if I want to create some functions that should be only be loaded when required, like it was with module_load_include() in D7. Though this function is still there in D8, I hear that this is not the best procedure. Is that so?

I have read somewhere, that using PHP traits is considered a better practice here. However, not sure if useing a trait inside a .module file is a good approach.

Any help?

Answer 1

Actually there seems to be nothing wrong about using *.inc files in D8. Have a look at the Update core module. Quite some *.inc files present: cgit.drupalcode.org.

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Nevertheless I tend to follow Symfony's best practice examples when it comes to stuff like that.

[Symfony Docs] Organizing Your Business Logic

[Stack Overflow] Where to put model helper functions in Symfony2

Means you'll add a new class under src/Utils. For example:

src/Utils/HelperFunctions.php
src/Utils/FooBar.php

And then wherever you need it, you reference it:

use Drupal\MYMODULE\Utils\HelperFunction;
use Drupal\MYMODULE\Utils\FooBar;

And then you'd call a certain function like so:

$site_color = HelperFunctions::getSiteColor();
$foo_bar    = FooBar::returnFooBar();

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And when I'm still unsure, I'll search inside the core and contrib modules how they did it.

Answer 2

In reference to the other answer, the main reasons those .inc files still exist in core is that was just not possible to rewrite everything into classes/services, which is definitely the right way to do it in Drupal 8.

Part by part, more and more functions are being converted to services in Drupal 8 and deprecated in favor of them. Instead of static methods, that's what you should do.

There are plenty of tutorials and documentation on how to create those services and use them, see https://www.drupal.org/docs/8/api/services-and-dependency-injection/services-and-dependency-injection-in-drupal-8 for example.

trait can be used when sharing common code between multiple classes that doesn't need to be exposed as it's own service. It's basically just a built-in copy & paste and similar to base classes but more flexible.