librarian VS Slim

2: Check get_structure() in https://gitlab.com/hsleisink/librarian/-/blob/master/libraries/directory.php.

Currently Laravel is the "go to" for new PHP applications to mostly developers today, if not, plain PHP, Slim, Symfony and other frameworks does the job, but for Wordpress, custom PHP boilerplates or/and outdated PHP patterns (aka, single ton) is what we have for work in mostly cases, if not, hacky ways to integrate frameworks as Laravel itself or parts of it to leverage a better code structure.

Slim is a micro PHP framework used for web development with 11.7k stars and 2k forks on GitHub. It has a simple and intuitive API development process. It is a micro-framework, meaning you only get a minimum of support for HTTP requests and forwarding requests to appropriate controllers. So the question is, why should you choose a micro-framework? Because it offers you flexibility and high extensibility.

Slim 4, a minimalistic PHP micro-framework, offers middleware support to easily add CORS headers. Middleware in Slim acts like a series of layers through which your app sends a request. One such layer can be responsible for adding CORS headers.

SlimPHP 3 Skeleton app shows this as well: https://github.com/slimphp/Slim-Skeleton/blob/3.1.8/public/index.php

How hard did you look? There are plenty out there. FastRoute, Phroute, based on FastRoute, with basic middleware, League/Route - routing with middleware, using FastRoute, PSR 7 & 15, Slim Framework, at it's core, it like League/Route, etc. None of these require a full framework to use.

You can have the container call in a config folder with a file called dependencies or how ever you want. A few existing examples of this is here - Slim calls this app/dependencies in this skeleton project and Odan's Skeleton has this as config/container in their project.

Maybe use this if you don't like to dive into bigger frameworks: https://www.slimframework.com/