Type checking during compile

[trivigy]

Sorry for the naive question in case this is really rudimentary but is there a way to type check the json instance during compile time? The basic use case in my situation is that I am passing a json object as a function argument and I want to ensure that only json::object is passed. Was hoping it could be check done during compile time.

[nlohmann]

I am afraid this is not possible.

[OvermindDL1]

Well, it 'is' possible in C++98 and higher, just will slow compilation a great deal (though not as much in C++14 and higher), and will require a JSON parser programmed via templates (which is entirely doable, Boost even has such a library for making such compile-time parsers), and I don't know of any off hand that are already made...

If you feel up for making such a library @trivigy then this is a popular link for parsing strings at compile-time first-steps: https://akrzemi1.wordpress.com/2011/05/11/parsing-strings-at-compile-time-part-i/

EDIT: One example of a very very simple string parsing is my string atom's converter that I made at https://github.com/OvermindDL1/OverECS/blob/master/StringAtom.hpp where you can do something like "blah"_atom64 and it compiles it to a packed encoding into a (in this case) 64-bit integer (or 32-bit for _atom32), it is reversible so you can get the string back out (limited to 5 chars for 32-bit or 10 for 64-bit of a restricted character set). It follows a similar pattern as this though.

[nlohmann]

I meant it is not possible with this library. But if you need compile-time checks, then of course you also need a compile-time parser.

[trivigy]

If I wanted to use another library I wouldn't post it here. But thanks for the recommendation. I was able to get away without depending on that check. So all good with using just `json ()` type.

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On Tue, May 22, 2018, 2:24 PM Niels Lohmann ***@***.***> wrote: I meant it is not possible with this library. But if you need compile-time checks, then of course you also need a compile-time parser. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#1103 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/ADABTgzsoQG6IIBrXdYeaFraH0DGdTBHks5t1FfrgaJpZM4UHbkq> .