On 11/16/2011 02:43 PM, Arun C Murthy wrote: > I propose we adopt the convention that a new major version should be a > superset of the previous major version, features-wise.
That means that we could never discard a feature, no? One definition is that a major release includes some fundamental changes, e.g., new primary APIs or a re-implementation of primary components. MR2 probably qualifies as both. With a large system with many APIs and components this becomes a rather subjective measure, but I don't see an easy way around that. Another definition is that a major release permits incompatible changes, either in APIs, wire-formats, on-disk formats, etc. This is more objective measure. For example, one might in release X+1 deprecate features of release X but still remain compatible with them, while in X+2 we'd remove them. So every major release would make incompatible changes, but only of things that had been deprecated two releases ago. Often the reason for the incompatible changes is new primary APIs or re-implementation of primary components, but those more subjective measures would not be the justification for the major version, rather any incompatible changes would. Of course, we should work hard to never make incompatible changes... Doug
