docstring support for functions

[melven]

Uses an additional (optional) argument in libcxxwrap-julia method functions to pass a docstring from C++ to Julia.

[melven]

Hi,

thanks for the nice work on CxxWrap.jl.
I'm not so familiar with Julia but the pybind11 binding for Python allows to add docstrings which I find extremel useful to build usable interfaces from C++ for python.

So I tried to implement something similar, passing a string from C++ to Julia which is used as a docstring.
Works together with JuliaInterop/libcxxwrap-julia#140
Currently only works for method, I didn't figure out how this should be done for add_type.

I don't know the workflow for merging some changes into both CxxWrap and libcxxwrap-julia, so I just opened 2 pull-requests for further discussion.

Thanks for looking into this and happy holidays!
Melven

[barche]

Thanks for this and sorry for my slow response. This is definitely nice to have, I'll look into this over the next week and at the same time figure out a new way to test PRs that change both C++ and Julia sides, since currently this is too difficult.

[sloede]

Facing the question on how to properly add docstrings and came across this PR... very nice! Are there any updates on if/when this might make it to a released version of CxxWrap.jl?

[melven]

[...] figure out a new way to test PRs that change both C++ and Julia sides, since currently this is too difficult.

At least for this case, it could work to update first libcxxwrap and then CxxWrap.jl: the only interface is the doc argument the CppFunctionInfoStruct:
After looking into the code for jl_new_struct, it seems to me that any additional arguments to jl_new_struct are just ignored (if the Julia struct has still fewer arguments).
The other way round (fewer arguments than needed) might not work (undefined behavior) -- the code in https://github.com/JuliaLang/julia/blob/b354ce7c41f0fd6caa8da115be38c53143a3d548/src/datatype.c#L1481 doesn't seem to check the number of va-args...

[barche]

I have pushed the changes here (plus the removal of the println to the testjll branch and merged the libcxxwrap-julia PR, so the CI there should now run with these changes. ONce this checks out I'll merge this manually.

[melven]

Thanks!

[barche]

Merged manually into main, can already be used by adding CxxWrap#main