initializer list constructor makes curly brace initialization fragile

[maddanio]

Hey,

I just discovered when i convert something to json on the fly like this:
nlohmann::json{my_value}
it turns it into an array, which is highly unexpected. this is a bit like the operator T() problem: too muc magic. I would be less dangerous if array/object construction where explicit, i.e. json::array({....})/json::object({{key, value},...). one can even make json::array/object objects and lose the round braces.

[nlohmann]

The problem is known, and changing it would be a breaking change...

[maddanio]

As for operator T(), right? I would say it should be part of the same discussion. Or a version 2 started, which has less magic and better composbility?

[olavurmortensen]

Would probably be a good idea to mention this in the documentation. The Cpp Core Guidelines recommend always using value initialization, so I expect a lot of people are doing that. Had this problem today, and it took me a good while to locate it, and didn't fully understand it before finding this issue.

[falbrechtskirchinger]

@olavurmortensen It is mentioned in the FAQ. Where did you look? In other words, where should it be mentioned to make it more discoverable? Probably at least the constructor, where I can't find it.

[olavurmortensen]

I've only read in the reference:
https://json.nlohmann.me/api/basic_json/parse/
and the README:
https://github.com/nlohmann/json#read-json-from-a-file
But I didn't see any mention of this there.