srenfo
commented
3 years ago I would steer clear of JSON [1][2] and YAML [3], except maybe StrictYAML [4]. Googling for "JSON configuration" had two articles advising against it in the first four results for me. You can find plenty about YAML issues and gotchas as well. I have had minor (JSON) to medium (YAML) issues using them as configuration myself.
On the other hand, with PEP 518 (pyproject.toml), TOML has become a first-class citizen in Python. Contrary to JSON and YAML, it was explicitly designed as a configuration language. The PEP discusses TOML and even includes a comparison table of TOML, JSON, YAML and INI. JSON Schema Everywhere has a section about TOML.
The articles above/below list Hjson, JSON5 and HOCON as further alternatives.
I do not have much experience with either TOML or the other alternatives, but just from the looks of it I suggest TOML.
[1] https://www.arp242.net/json-config.html [2] https://www.lucidchart.com/techblog/2018/07/16/why-json-isnt-a-good-configuration-language/ [3] https://www.arp242.net/yaml-config.html [4] https://news.ycombinator.com/item?id=17358103 (thread with the creators of YAML and StrictYAML weighing in, with some noise)
glaslos
For #525 I had to write some XML which was rather unpleasant... I'm suggesting to replace our use of XML for defining the templates with something more human readable, suggestions welcome. I would definitely like to maintain the ability to verify a template with a schema. Whatever we decide to replace XML with, doesn't need to support a schema. but we can verify the JSON we parse from the template.