About squeak image compatibility (3.6/7/8)
Adrian Lienhard
adi at netstyle.ch
Mon Jan 9 11:08:30 UTC 2006
On Jan 9, 2006, at 07:20 , Andreas Raab wrote:
> Cees De Groot wrote:
>> Could you substantiate that claim? I think that Traits introduces
>> extremely little compatibility issues...
>
> Well, I think that depends a *lot* on your perspective of the
> system. It would be more accurate to restate the above to say that
> there should be very little compatibility issues, UNLESS:
>
> * you actually start using 3.9, in which case you'll have issues
> with porting back stuff to older Squeak versions (this will be a
> serious issue for packages that are and should be used in older
> versions of Squeak - will these older versions of Monticello be
> able to deal with class definition that have been created in 3.9? etc)
yes, you can load packages built with a MC 3.9 version in an older MC
version if the package does not include traits.
> * you assume a stable interface in classes and meta classes (this
> got seriously broken in 3.7, then again in 3.8, and now again in
> 3.9 - it is amazing how little continuity there has been in such a
> critical part of the system)
For traits, we tried to maintain the existing class/metaclass
interface as much as possible. Do you have a concrete problematic
example where this is not the case?
> * you use meta tools that rely on the previously available semantic
> entities (which excludes traits)
>
> * you use meta tools that rely on previously stable representations
> (class definitions in particular)
> Now, I'm not saying that everyone will be affected by (or even care
> about) the above but if you are in either situation it is pretty
> safe to assume you'll be severely screwed one way or another. Case
> in point: Without appropriate fixes Monticello and file contents
> browser are invariably broken (and so is the VW parcel that allows
> people to load Squeak code).
Do you have examples?
Cheers,
Adrian
> And of course, another major difference in perspective is whether
> you are on the breaking or the broken side of things. People don't
> like their stuff to get broken by other people so any claim that
> this is "extremely little" is not likely to get you many friends -
> in particular if the breakage (as so often) is undocumented and
> you'll probably find out the hard way. And I think you'd be well
> advised to keep that in mind.
>
> Cheers,
> - Andreas
>
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