It isn't meant to be used by itself, but as template for your our types.
Attempt to do Efficient Programming with Components: Lecture 2 Part 1, Efficient Programming with Components: Lecture 2 Part 2 and Efficient Programming with Components: Lecture 3 Part 1 from C++ to Ruts.
[1] https://www.youtube.com/watch?v=FUMPsmKnKv8
[2] https://www.youtube.com/watch?v=B5yiLvaxPS4
[3] https://www.youtube.com/watch?v=sp_IBYVqMeQ