collections VS Deptrac

Theoretically, our domain should only contain pure PHP code without any external dependencies. Nonetheless, there are some libraries that we want to use in our domain, such as ramsey/uuid to generate UUIDs, or brick/math to work safely with numbers. Another usual example of an allowed external library in our domain is doctrine/collections when we use Doctrine as an ORM, because the relationships between entities must be of type Doctrine\Common\Collection.

How you want to do the grouping is up to you. Maybe look into using Doctrine Collections: https://www.doctrine-project.org/projects/collections.html

You can also look at Doctrine Collections as an example of a library doing something similar and making full use of generics. Look at all the annotations that mention `T` or `TKey` in https://github.com/doctrine/collections/blob/c1ec9823f9250fefb274cccf62970b5c167e6bc7/lib/Doctrine/Common/Collections/Collection.php

Deptrac

Deptrac: Keep your architecture clean.

So far I've found some tools which I could piece together to accomplish enforcing module boundaries, probably run as part of an automated github action. - https://github.com/qossmic/deptrac Uses YAML to define any boundary, you can also use @internal to hide implementation classes. Seems like a good way to achieve what I want.

How about https://qossmic.github.io/deptrac/ ?

>I wonder: Is automatic DI even helpful? You save some lines of boilerplate but sacrifice control over the initialization-order and get a flat, messy, implicit dependency graph

Initialization order doesn't matter if your services are stateless. At least in our codebase, all of them are stateless, as it greatly simplifies reasoning about concurrent code (both in-process and between servers). Yes, it's easy to end up with a very a convoluted dependency graph under the hood, but I don't think it's a problem you really should care about. I mean, your code most likely already compiles to a very convoluted mess of machine code under the hood (with all the optimizations, ABI quirks etc.) and I doubt it matters to you much, as long as it does its job well and doesn't hinder your productivity.

If you are talking about messy dependency graphs from the architectural standpoint (someone can easily add a dependency in the constructor without thinking about the consequences), we use deptrac for our PHP monolith which can validate your architecture is clean at build time [0]

However, for our microservices written in Go, we decided to use manual DI to stimulate developers to prefer simpler design, otherwise our microservices could quickly turn to monoliths again.

[0] https://github.com/qossmic/deptrac

Deptrac is a static code analysis tool for PHP that helps you communicate, visualize and enforce architectural decisions in your projects.