Struct polymorphism?

[Era Scarecrow]

On Sunday, 7 October 2012 at 10:04:57 UTC, Era Scarecrow wrote:
> What are the possibilities of struct polymorphism? What would 
> be the issues with it? What if we wanted to use it in a limited 
> sense?
>
> Currently I'm experimenting with it since classes are too bulky 
> for what I need, yet I really need some type of 
> behavior/dynamic polymorphism. So far I have a working model. 
> It takes the following limitations:

  A question of efficiency comes up. If at compile-time we can 
confirm only a couple branches/possibilities, then only those are 
considered during run-time. During optimization is that code just 
inlined to where it is called rather than the jump to opDispatch? 
Seems like it should if it's small enough, especially if there's 
only 1 possibility.


  Now I guess a question out there for you all. Who would be 
interested in an implementation and how would you use it? Does it 
seem like a good idea? How many levels would you want to use? 
One? Several levels allowing class-like inheritance?