Any way to tell if an object is inside another class?

[Ruby The Roobster]

On Monday, 28 September 2020 at 14:09:07 UTC, Paul Backus wrote:
> Can you re-write this as actual valid D code, but with the 
> implementation of the function stubbed out? I still don't 
> understand what your function is supposed to take as its 
> input(s), or what "parent object is a member variable of an 
> aggregate type" means (as far as I'm aware, objects are 
> *values*, not *variables*), or what UDAs have to do with any of 
> this.

I meant User Defined types. not UDAs. Anyways, the whole thing is 
me trying to find a hacky workaround that allows something 
similar to multiple alias this declarations(because multiple of 
these are not possible). And for this, I have to determine if a 
normal number is being passed, or if an user defined type is 
being passed through the parameter.