Should Extension inherit from ExtensibleEntity?

[mbrush]

IMO we want Extensions themselves to be extensible (e.g. as they are in FHIR). If this is the case, we should make the Extension class inherit from ExtensibleEntity in the core-source.yaml file.

[larrybabb]

@mbrush I don't agree with adding this complexity until we have an implementer that asks for it. It is not necessary at this time so I would suggest we archive this discussion and re-raise if/when it is requested for an implementer's use case.
@mbrush I will defer to you to close this for now if you agree. So we can get our issue list down to the most pertinent issues.

[mbrush]

Hi @larrybabb - this ticket is quite old, and was written when there was an ExtensibleEntity class in the model. There is not anymore, and the extension property is now defined on Entity.

So the relevant questions now are:

• Do we want Extensions to be extensible?

  • I see value in permitting this - give users flexibility that efforts like FHIR have deemed useful enough to include in their model. But I am ok with passing on this for now as you suggest - until it requested by an implementer.

• If we do want Extensions to be extensible, we either need to have them inherit from Entity, or define an extensions field on them directly.

  • I would prefer the latter (I don't think Extensions need all the other properties defined on Entity). But again, this second question is only relevant if the answer to the first question is 'yes'

I will go ahead and close this ticket - but others can re-open if/when they want to explore this more.