Please add support for calling methods from C++

[Envek]

In #50 and #281 there said that Ruby FFI not currently supports C++ libraries with mangled method names.

Question: is it hard to add support for such C++ libraries?

So, If I have a library with custom.h with code like:

int scaleImg( unsigned char *BufImg, int &Maxx, int &Maxy, int Dpi );

and implementation like:

int scaleImg( unsigned char *BufImg, int &Maxx, int &Maxy, int Dpi ) {
    callCplusplusTemplatedFunction(param);
    doSomethingElse();
}

And I have compiled libcustom.dylib with this function, so nm -gU libcustom.dylib | grep scaleImg returns something like this:

0000000000046410 T __Z8scaleImgPhRiS0_i

And I would be happy if I could write something like this:

module Custom
  extend FFI::Library
  ffi_lib 'custom'
  attach_function 'scaleImg', '__Z8scaleImgPhRiS0_i', [:buffer_inout, :int, :int, :int], :int
end

And it will work.

If it's hard, can you add more detailed info to the README or wiki for how to make a C-style stub lib to call methods from C++-style .so or .dylib when I can't change this library (or it's hard as it heavily uses C++ stuff like templates and classes) and I have it's header files.

Thank you in advance.

[Envek]

Actually I was able to use mangled name (omitting first underscore from it):

attach_function :scaleImg, '_Z8scaleImgPhRiS0_i', [:buffer_inout, IntPtr, IntPtr, :int], :int

Thank you for FFI — it's awesome!