C API

[VarLad]

I would love to use this in projects outside Zig as well.
Any idea if this project can provide a C API?

[david-vanderson]

Good idea! I haven't thought about this before. Just to make sure, are you thinking to compile dvui into a static library and call the functions from C?

I think this should work with some modifications (adding extern to various functions). Give me some time and I'll try to make a prototype example.

[VarLad]

@david-vanderson Yeah, exactly that
Ideally the project could provide a C header file one can easily use.

[iacore]

@VarLad you might be better off using imgui with C. Zig has types like ?T that is incompatible with C ABI.

[david-vanderson]

I also recommend dear imgui, but I suspect you already know about it. In any case it will still be useful to see if exposing a C API can be done.

[iacore]

It can be done but it is difficult.

Every error.X need a fixed number to map to it.
Every enum variant need a fixed number to map to it.
union(enum): not exist in C.
?T: not exist except optional pointer.

[david-vanderson]

I spent some time digging into this. It seems like this should be possible, but is currently not well supported.

ziglang/zig#9698 looks like the tracking issue for this in zig. I was able to use zig build-lib -femit-h=test.h test.zig to autogenerate a header for exported functions, but then ran into ziglang/zig#14381. All my attempts via build.zig also failed, sometimes with an error like error: unable to create compilation: NoZigModuleForCHeader

And this is all before getting into the issues that @iacore listed.

@VarLad It looks like this isn't the right time to attempt this, do you agree? Maybe we should revisit this after zig 0.12 is released and see if things have gotten better.

[VarLad]

I agree with that. We can revisit the issue after Zig 0.12 release.

[Renha]

The tracking issue has 0.13.0 milestone set 😭

[david-vanderson]

Good point. If 0.12 doesn't fix it, then we might have to try doing it "manually" - using -femit-h but hand editing the output.

[VisenDev]

I did a little bit of testing related to this in C. It does appear to be possible to recreate zig's @src() in C (which is something I thought might be a problem for using dvui with C)

#include <stdio.h>
#define SRC {__FILE__, __LINE__}

typedef struct {
    char*file;
    int line;
} Source;

int main() {
    Source a = SRC;
    printf("%s%i", a.file, a.line);
}

[david-vanderson]

That is very interesting - well done!