[Grace-core] inheritance for stateless traits and beyond

[James Noble]

> On 26/06/2015, at 10:37am, Andrew P Black <black at cs.pdx.edu> wrote:
> 
> I continue to believe that the traits system for Smalltalk did a good job.  The original ECOOP paper (and the later TOPLAS paper) discuss all of the problems with prior approaches and how traits solves them.  This was more than 10 years ago now.

sure. 

> Since then, roughly a dozen other languages have adopted some version of the traits solution.  In the spirit of Grace taking advantage of recent research on PLs, don't you think that we should look at this work, rather than pretending that it doesn't exist?

I’m not ignoring it. 
The question are
  - which problems that traits solve do we need to solve?
  - which parts of the traits mechanism do we need to solve just those problems?
  - how to incorporate those parts into the existing Grace design?

for me, I think it is worthwhile combining multiple parts of objects together
to promote planned reuse (particularly of dialects) which seems to be key to traits.
I’m less convinced on the additional features of traits (for ad-hoc reuse), many 
trait systems (Scala etc) don’t have that. 
Then there is the question of how to fit it in to Grace.

James