Everything about TOML format - Orchard Dweller

ruffsl@programming.dev to Programming@programming.dev – 43 points –
Everything about TOML format
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Every time I have reached for TOML I have ended up using JSON. The first reason is that Python standard library can read but not write TOML, which is generally useless for me. The second reason is TOML does not add any benefit over JSON. It’s not that much easier to read and IMO JSON is easier to write by hand because the syntax rules are completely obvious.

TOML is mainly for humans to write, certainly not a good choice if you're programmatically writing files - comments and formatting would be lost.

It all depends on the library you use. Rust has you covered with toml_edit. It is what is used for all the cargo commands editing the Cargo.toml file.

Agreed. Except that it’s not easier to write imo

Where do you put your comments in JSON files?

I've seen them included as part of the data.

"//": "Comment goes here",

Example here.

That doesn't really work when you need two comments at the same level, since they'd both have the same key

write json with comments. Use a yaml parser.

If you're reaching for yaml, why not use toml?

because of the cut and paste problem. It works in json.

Cut and paste problem?

cut out a random piece of your document. is it a partial or a complete document?

paste it somewhere else in the document. you have to fix the indentation because if not then the document won't work or mean something completely different

you have to fix the indentation because if not then the document won’t work or mean something completely different

Whitespace has no meaning in json. You can indent however you want, or not at all.

I'm assuming you're running into issues because you're writing json in a yaml file which does care about indentation, and you're only writing json in yaml to get access to comments.

In which case it circles back around to: why not use toml? Whitespace formatting doesn't corrupt the file, and it has built in comments.

i do use json instead of yaml precisely for the reasons you mentioned. That was my original point in the first place that json does not have these problems. something must have been lost in transmission

It still works since multiple identical keys are still valid json. Although that in itself isn't fantastic imo.

For settings files I always have an example file with sensible values filled in and along with descriptive keys that serves as reasonable documentation. If something is truly unknowable, I’ve probably done something wrong.

How would you mark a flag in your json settings file as deprecated?

In my opinion, the settings file isn’t where this information should be presented. I would put these notes in the release log and readme and example settings file. I have also written this information to logging during startup so a user knows what to do, or I write a migration that does the change automatically if that’s possible.

This is only my opinion and you can use the comment method described like “//“: “Deprecated” if desired.

The very first moment that I had to use JSON as a configuration format, and I was desperate to find a way to make a long string into a JSON field. JSON is great for many things, but it's not good at all for a configuration format where you need users to make it pretty, and need features like comments or multi-line strings (because you don't want to fix a merge conflict in a 400 character-wide line).