Several years ago, when the PHP-FIG (PHP Framework Interop Group) created its first PSRs (PHP Standard Recommendations) they started some big changes in the PHP ecosystem. The standard for class auto-loading was created to go hand-in-hand with the then new package manager Composer. PSRs for coding standards were defined, which I’m sure helped a lot of teams to leave coding standard discussions behind. The old tabs versus spaces debate was forever settled and the jokes about it now feel quite outdated.

During a recent run of my Advanced Web Application Architecture training, we discussed the distinction between infrastructure code and non-infrastructure code, which I usually call core code. One of the participants summarized the difference between the two as: “everything in your vendor directory is infrastructure code”. I don’t agree with that, and I will explain why in this article.

Not all code in vendor is infrastructure code

Admittedly, it’s easy for anyone to not agree with a statement like this, because you can simply make up your own definitions of “infrastructure” that turn the statement false. As a matter of fact, I’m currently working on my next book (which has the same title as the training), and I’m working on a memorable definition that covers all the cases. I’ll share with you the current version of that definition, which consists of two rules defining core code. Any code that doesn’t follow both these rules at the same time, should be considered infrastructure code.