using shared libraries from other languages

[visr]

I'm interested in using this package for creating shared libraries that can be used from Fortran (or any other language that supports calling C-exported shared libraries).

Currently the shared libraries created here do contain the @ccallable functions given in the julia script. But if I'm correct these cannot be used directly because you need to call jl_init first, and anything else mentioned in the embedding docs. This is done in program.c, which is compiled to executable.

If I want to be able to call simple julia functions like Base.@ccallable f(x::Float64)::Float64 = 2.0 * x from a shared library, how would I go about that? Modify the program.c to compile as shared library and provide the initialization functions from libjulia there as well? If anyone could provide a minimal example that would be great.

I tried things like:

extern double f(double a);

#ifdef _OS_WINDOWS_
__declspec(dllexport) __cdecl
#endif
void my_jl_init(void)
{
    jl_init();
}

#ifdef _OS_WINDOWS_
__declspec(dllexport) __cdecl
#endif
double my_f(double a)
{
    return f(a);
}

But while my_jl_init seemed to work, if I do my_f after, it segfaults. Is this more or less the right approach however?

[NHDaly]

Is this related to the work done here?:
#25

I agree, this would be very cool.

[visr]

Yeah it is related, especially the emit_shared_julia, maybe I should try to adapt #26 (ignoring the Python specific parts).

If that would work it is probably worth it in itself, even if the python-c extensions aren't working yet.

[SimonDanisch]

That sounds like a good idea! Let me know if you have any questions or need help to get that PR running for e.g. C!

[visr]

To be honest I'm struggling with getting a simple example shared library to work manually. If I can get that to run, I agree it would be nice to automate in a PR.

Is my first post more or less along the right lines? Maybe I should not try first on Windows haha.

[Petr-Hlavenka]

See if #122 fulfils your needs - is already part of the 0.5.0 release for 0.7/1.0. In that case, the issue can be closed.

[visr]

Ah great, looks like it does! Thanks for letting me know.