Göran  Hultgren wrote:

> I don't think anyone is clear on how these things should work. :-) Object
> migration problems are generally tricky. Perhaps we should see if we
> couldn't handle many of these migration problems in a more... declarative
> way. Personally I haven't used pre/post-stuff that much so I don't really
> know how they mostly are used but IF they are mainly used for rather trivial
> migration problems then perhaps we should add some form of "rigour" to it
> and instead add some support to DeltaModules to specify those
> migrations/transformations in a declarative way?
> 
> It would sure make the modules system "safer" than having arbitrary code
> running... And it could tell you what it's doing, perhaps be able to
> revert/undo, warn and even abort depending on personal Preferences etc.
> 

Migration is tricky so I'm rather certain that any given subset would be
either safe or useful, but hardly both. Such code needs to be able to do
very unsafe things sometimes. I think class recompilation already takes care
of the easy transitions.

However, it will be evident in the module definition file that something
unsafe is done as part of module activation, so it would be easy to warn
about it.

Henrik