[your_fin]

> It almost always breaks every possibility to programmatically process or analyze the config. You can't just JSON.parse the file and check it.

Counterpoint: 95% of config-readers are or could be checked in with all the config they ever read.

I have yet to come across a programming language where it is easier to read + parse + type/structure validate a json/whatever file than it is to import a thing. Imports are also /much/ less fragile to e.g. the current working directory. And you get autocomplete! As for checks, you can use unit tests. And types, if you've got them.

I try to frame these guys as "data values" rather than configuration though. People tend to have less funny ideas about making their data 'clean'.

The only time where JSON.parse is actually easier is when you can't use a normal import. This boils down to when users write the data and have practical barriers to checking in to your source code. IME such cases are rare, and most are bad UX.

> Side effects in constructors

Putting such things in configuration files will not save you from people DRYing out the config files indirectly with effectful config processing logic. I recently spent the better part of a month ripping out one such chimera because changing the data model was intractable.