DeltaStreams moving forward

Göran Krampe goran at krampe.se
Thu Sep 6 07:36:48 UTC 2007


Hi!

> A small remark about #asAntiDelta.
>
> I think its better to rename it to one of:
> #asReverseDelta
> #reversed
>
> then code can look more nicely:
>
> self reversed apply
>
> or even:
>
> self reverseApply  (which will do exactly 'self reversed apply')
>
> I'm just don't like word 'Anti' in this context. For me, a words
> 'reverse changes' have more closer meaning to 'undoing changes' than
> 'anti changes'.

Possibly so, yes, I probably agree. The base idea is of course that we
only have one #apply method and we accomplish its "opposite" by instead
constructing a Delta that does the opposite.

There are also other "distinctions" we could make. For example, will a
revert be exactly the same as if I had manually made changes to undo the
previous changes? Or would it be exactly like an undo - leaving no trace
that the original changes ever happened (like for example "versions" of
methods)?

And if we want both mechanisms - what will we call them? Should we use
#revert (that does "self asReverseDelta apply" and thus adds a new Delta
to the list of "applied Deltas") and #unapply for this "real" undo
mechanism (that I guess would actually remove the Delta from the list of
"applied Deltas")? Or is a real undo even considered a dangerous idea?

Darcs has them both IIRC.

And oh, lists of applied Deltas etc - these are also "new concepts" in the
Squeak realm. SOooo many questions... :)

regards, Göran




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