> So, what I basically want to know is if what I wrote is valid and sound Nim
> code.
It is valid code. However:
You don't actually use inheritance in your code for `Fighter` and `Thing`, so
`of RootObj` and `method` (instead of `proc`) may introduce unnecessary
overhead, unless you plan on using inheritance later. If you do want to use
inheritance, then you may want to mark the root objects of your own inheritance
hierarchy as `{.inheritable.}` instead of inheriting from `RootObj`. Inheriting
from `RootObj` means that you can assign anything to variables of type
`RootRef`. This can be useful (e.g. for debugging purposes), but also means
that you can possibly get types mixed up.
Concepts (in their current form) are somewhat orthogonal to inheritance, as
they're (currently) for compile-time polymorphism (via generics) instead of
runtime polymorphism (which is what inheritance is for). Once `vtref` support
is available, you can then also use them for runtime polymorphism (see the
manual for details).
