Hi!

> On 02/10/2007, Jason Johnson <jason.johnson.081 at gmail.com> wrote:
>> Just because MC2 exists doesn't mean there is no room for competition.
>>  Personally I am quite interested in the Change set replacement part
>> of deltas.  I started down this road myself but Göran got further
>> faster.
>
> Sure, but I don't really see the point of developing two similar
> systems to manage changes (at least from the high level view). That
> said I prefer to see manpower employed for parallel tracks rather than
> for arguing which track is best :)

AFAIK they are quite different. From the highest level I would guess MC2
is an "SCM for team work on packages" very much like MC1 is - I mean, it
mainly covers the same usage area. It uses complete history to perform
very precise merging (again, similar to MC1, right?) and I would also
guess it uses some mechanism to "stake out" a package (PI?) and take
snapshots of it at given times. Those snapshots I presume are either
loaded-and-applied or not-loaded-at-all. Yes, MC1 has the "browse" feature
- but it is AFAIK mainly used to "take a peek".

Please correct me if I am wrong above - I have not yet read an explanation
of MC2 that gives me a good picture (and that is probably more due to *me*
than due to the explanations).

Deltas (and streams of them) on the other hand are ChangeSets "done right"
:). A Delta can be loaded into the image but not applied. It is then a
fully self contained object graph and is not affected by changes (unlike a
ChangeSet which only refers to methods and do not actually contain the
versions of them) in the image. Then you can apply it to the image and you
can also revert it.

Now, without going into other smarts in Deltas the above opens up
interesting options - like having a whole set of Deltas you can apply in
series and revert in series too. A simple scenario is maintaing a local
"patch series" on top of upstream packages. When upstream releases a new
version you "lift" your local patches (revert them), upgrade the package
(using say MC1/2), then reapply your local patches on top. Since the
Deltas are made to be able to do "the reasonable thing" WITHOUT history
analysis, this sounds to me like an interesting use case.

In short: I think the two code bases are quite different and aim for
different goals. But we touch upon "cooperative ground" like SystemEditor
and SystemChangeNotifier etc - both of which we have improved in our work
on Deltas - so cooperation and mutual understanding is *important* but I
do not think the two systems are that much overlapping in the end. I can
always be proved wrong. :)

regards, Göran