A thought experiment:
         A package is a bounded object space.
         Many versions of a package can coexist in an image.
         Any version can replace any other
                 if they are identical.
         A version can replace different one,
                 but only under under certain conditions.
         The base Squeak release is a package.
         A package that uses/builds on another package identifies
                 this package and its version
         My NewStuff package declares that
                 it merges any number of (package/version).
         When somebody runs MyStuffmuch later, MyStuff will still use
                 the proper package/versions.

         If MyStuff is popular, I might later update it to use a newer 
package/version to reduce total system complexity.

I know - this may be just a dream. May be somebody has done the research 
already.

For what it may be worth
--Trygve


At 05.11.2003 10:16, you wrote:
>On Wed, Nov 05, 2003 at 09:38:11AM +0100, Marcus Denker wrote:
> > What about this: While your programm is running on Squeak 3.5, it generates
> > instances of Objects and calls methods on them, resulting in a differnt
> > instance/changed instance. Couldn't we record these instances? with
> > state1/methodcall/state2 we have everything we'd need for building tests
> > automatically. This test-suite would be an exact testsuite in the sense
> > of "Program X thinks the environment should behave this way".
> >
>... lots of data. Too much, of course.
>
>One of the most underestimated features of a System is that it
>it perfectly possible to simulate other Systems. This enables
>to do "Backward-Compatibility" in a much more interesting way:
>By simply simulating the old system. This is something we should
>really look into, I think.
>
>For the idea stated above, this has the direct consequence that
>you don't need to build the testsuite (which would be too huge).
>
>Just run the Programm in both environments simustanly. Then you can
>nicely see if the old behaviour is the same as the new one.
>(I have no Idea how this would work in practice, though).
>
>           Marcus
>
>--
>Marcus Denker marcus at ira.uka.de  -- Squeak! http://squeak.de


-- 

Trygve Reenskaug      mailto: trygver at ifi.uio.no
Morgedalsvn. 5A       http://heim.ifi.uio.no/~trygver
N-0378 Oslo           Tel: (+47) 22 49 57 27
Norway