I am trying to migrate C++ code by compiling Kotli...

# kotlin-native

[Robert]

I am trying to migrate C++ code by compiling Kotlin to a dynamic library and replacing step by step.
I load this lib by including the header and the symbols:

#include "libmy_api.h"
auto mylib = libmy_symbols();

So far so good. Now I would love to replace the orginal classes, for example CMyClass with the one from the Kotlin library. So I remove CMyClass from the C-source code, and I add a typedef:
typedef libmy_kref_MyClass MyClass;
Now I can use the regular MyClass as a type: std::vector<MyClass> classes
So I don't have to touch that code, as it was already referencing "MyClass". Still good.
Now the problem is when I try to create an instance. The current code is like this:
classes.push_back(MyClass())
But to initiate the class in the KN dl way, I have to replace all the code with:
classes.push_back(mylib->kotlin.root.MyClass.MyClass())

Is there a way, like typedef or using does, to keep this code intact while it does actually reference the kotlin generated dynamic library?

[olonho]

Not sure if C API can be drop in replacement for C++ classes, and we got no C++ interop yet

[Robert]

But C++ can load a C library afaik, so I think that will work. Also the first example works, I just don't know how to type-alias the creation of the instance. I tried with ->, ::, 'struct`, * and all that in the typedef, but it seems it is not allowed. I'll try to create a small example later today.

[YoshiRulz]

It seems that the "classes" in the generated dll aren't intended to be instantiated from C++/Rust/whatever. If you use StableRef you can pass objects between Kotlin and C, but they can't be modified by C code like structs can.

[Robert]

I don't understand, I thought this was the whole purpose of it?

[Robert]

So something like this would never work?

#include <iostream>
#include "libmyn_api.h"

auto mylib = libmy_symbols();

using CPerson = libmy_kref_Person;

int main() {
    CPerson person = mylib->kotlin.root.Person.Person("firstname", "lastname");
    std::cout << "Hello, " << person.lastname << std::endl; // error on lastname, only "pinned" available"
    return 0;
}

[Robert]

This works mylib->kotlin.root.Person.get_lastname(person).
Now I only need a way to shorten it to something like Person.get_lastname(person) and a simple way to create a new instance, preferable like it was before (Person("first", "last"))

[Robert]

I figured to get it this good:

auto personlib = mylib->kotlin.root.Person;
 auto person = personlib.Person("first", "last")
 std std::cout << "Hello, " << personlib.get_lastname(person) << std::endl;

But as i'm very unexperienced with C++ there probably is a cleaner and more generic way.

[Robert]

Too bad it results in Process finished with exit code 139 (interrupted by signal 11: SIGSEGV)

[Robert]

https://kotlinlang.org/docs/tutorials/native/dynamic-libraries.html

There is a constructor in the Clazz field (aka kotlin.root.example.Clazz.Clazz), which is the constructor function to create an instance of the Clazz.

Should be possibe to create an instance..

[Robert]

Anyone knows how to resolve this error when using a compiled dynamic library?
Process finished with exit code 139 (interrupted by signal 11: SIGSEGV)
It happens when i try to create an instance.

[Robert]

Anyone? 😞

[Robert]

I commited the project to github. Maybe someone can spot what I did wrong? Where should I look - the cmakelist? Or the library itself?
https://github.com/RdeWilde/kotlin-dl-test
Process finished with exit code 139 (interrupted by signal 11: SIGSEGV)
on this line https://github.com/RdeWilde/kotlin-dl-test/blob/master/main.cpp#L9

[Robert]

This has been resolved! https://github.com/JetBrains/kotlin-native/issues/3604