by Paolo G. Giarusso and Jonathan Immanuel Brachthäuser

Technical report. Talk at Scala Symposium 2016, University of Tübingen, Germany, 2016.

Abstract

The cake pattern was designed to support modular development combining mixins with ML modules, but it is criticized because mixins are not sufficiently isolated from each other’s implementation. Indeed, as discussed by Gabriel, historically mixins were not designed to enforce isolation, but to support separating intrinsically orthogonal concepts in cooperative development scenarios. We start investigating the issue and clarify which scenarios the cake pattern does succesfully apply to. We compare the cake pattern with an encoding of (recursive) hierarchical modules based on object composition instead of inheritance, that support fully separate modular development at the cost of more boilerplate. We also suggest one could support separate modular development without additional boilerplate by combining the cake pattern with private implementation inheritance.