IdentityObject & abstract superclasses

Dan Smith daniel.smith at
Thu Aug 27 00:09:45 UTC 2020

> On Aug 26, 2020, at 3:36 PM, Peter Levart <peter.levart at> wrote:
> I apologize for not reading the previous discussion about "Superclasses of inline classes" (as of 19th of dec. 2019). I now see the intent was to not use a special class modifier to express the feature of light abstract class.
> The intent was also to allow extending "light" abstract classes with inline as well as non-inline classes. In that case, a modifier like "inline" would be a strange way to express such thing.

Yeah, you got it. (No need to apologize for missing an 8-month old thread!)

Given the numbers I cited, the motivation for doing this implicitly is that about 25% of existing abstract classes should be totally fine to extend with an inline class. If those classes have to explicitly opt in, most never will, limiting the usefulness of inline classes. (Similarly, imagine how it would go if you could only implement interfaces that explicitly permit inline subclasses.)

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