Rice is a C++ header-only library that serves dual purposes. First, it makes it
much easier to create Ruby bindings for existing C++ libraries. Second, it
provides an object oriented interface to Ruby's C API that makes it easy to
embed Ruby and write Ruby extensions in C++.

Rice is similar to Boost.Python and pybind11 in that it minimizes boilerplate
code needed to interface with C++. It does this by automatically determining
type information allowing Ruby object to be converted to C++ and vice versa.