How to wrap C++ function writing to FILE*?

General Usage
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1

I want to wrap a C++ function writing to a file stream to be able to print to a file or to stdout (eventually I’d like to try if redirect_stdout would work to make it print to a custom buffer). However, CxxWrap does not want to export it saying there is no factory for the IO_FILE type. As far as I understand, such functions are supposed to take Ptr{Libc.FILE} from Julia. Is it possible to do that using CxxWrap?

For the reference, the C++ library in question is Voro++. It has some output functions that use protected and private class members internally, so that I cannot just port the implementation to Julia without patching the original library.

2

Okay, I think I have found out a way to do that.

Instead of adding the needed method automatically via CxxWrap, I added a C wrapper function like the following:

extern "C" {
    void write_data(Object* obj, FILE* fp)
    {
        obj->write_data(fp);
    }
}

And from Julia, I use ccall directly:

function write_data(io::IOStream, obj::CxxObject)
    file = Libc.FILE(io)
    ccall(
        (:write_data, "libmywrapper"),
        Cvoid,
        (Ptr{Cvoid}, Ptr{Libc.FILE}),
        obj.cpp_object, file,
    )
    close(file)
end