Is there a way to add nlohmann json as a a single pair of hpp/cpp?

[DamirTenishev]

The single include option is very handy, but when it comes to debug application which loads large json files, it becomes too slow.

I want to have an option like a single pair hpp/cpp so that I could compile cpp details in release mode even in debug project in order to make it fast.

For sure I can take all the sources and build a library or add all of them to my project, but this would be a long way. Am I missing a simple way to download such a pair?

[gregmarr]

It's most likely slow in debug builds because the debug standard library adds extra error checking, and the optimization level is reduced, so the compiler does a lot less inlining. You should look at making sure that you have optimizations enabled for your source files that include the library. This may require restructuring your code a bit to keep the JSON-accessing code isolated from the rest of your code so that you can compile it with different optimization flags. You'll still take any hit from using the checking version of your standard library. This can be especially significant if using Visual C++.

[DamirTenishev]

Of course, your solution came to me, as well, and I used it as a "first workaround", but I am not happy with it.

The key is that I never need to debug into nlohmann json, so I need a release version only of it both for my release and debug versions, like I have for dozens of libraries and APIs. I want "fire and forget" solution without risky options, code restructuring, etc.

I agree that the cause if close to what you've described. At the same time I am not sure your approach is the simplest. I don't like to introduce additional build configuration and get risks related to switching compilation options (with a chance to switch back). Having a standalone release lib file or cpp file with all the source would be much better, since I will be able to change settings to this file only. Not sure that this is a real problem to have a cpp or lib.

(Yes, you are correct, I am using Visual C++).

[gregmarr]

(Yes, you are correct, I am using Visual C++).
The key is that I never need to debug into nlohmann json, so I need a release version only of it both for my release and debug versions, like I have for dozens of libraries and APIs. I want "fire and forget" solution without risky options, code restructuring, etc.

The problem there is that it uses the standard library types like std::vector, std::map, and std::string. It's extremely difficult if not impossible to have both the release and debug versions running in your process at the same time. You have to be absolutely sure that you never take an object created with the release version and operate on it with code that is built with the debug version, or vice versa.

Having a standalone release lib file or cpp file with all the source would be much better,

It's all templates, so there's no such thing as "a cpp file with all the source". The source is all in the class declarations in the headers, because it has to be.