Is it possible to elegantly craft a class that can be used as shared and as normal?

[Gary Willoughby]

On Sunday, 2 March 2014 at 18:04:06 UTC, Dicebot wrote:
> shared and non-shared entities have different implementation. 
> You unlikely want to have one for both.

It's part of my unit-testing toolkit that handles mocking of 
objects. I want to use the same code to handle shared and 
non-shared entities.