[squeak-dev] All Clear (and Monticello issues)

Colin Putney cputney at wiresong.ca
Tue Sep 1 18:38:10 UTC 2009


On 31-Aug-09, at 12:58 PM, Eliot Miranda wrote:
>
> Which ever approach one takes, a safer order or a truly atomic  
> install, I think the right approach is a plan/execute one (a.k.a.  
> compile) where the various updates are created as a sequence of  
> operation objects before being run together in some context, instead  
> of interpreting.
>
> Presumably (Hi Colin,) the MC2.0 atomic install works somewhat like  
> this.  The question is therefore whether one should try and extract  
> that from MC2 or move to MC2 adding backward compatibility to load  
> MC1.5 format packages.

Yes, SystemEditor does work like this.

The idea is that you make your changes using protocol-compatible  
proxies for the actual classes, called editors. The editors record the  
changes then when the transaction is committed, build new classes,  
(re)compile methods and migrate instances. If all goes without  
incident, it's all installed with a mass become.

There's no need to extract SystemEditor from MC2 - it's a separate  
project already in use in a couple of other places.

As far as moving to MC2 goes, I do think we should do that eventually.  
It's not quite there yet, though. The 2.0.x releases had some  
logistical issues which made them awkward for collaborative  
development. I'm currently at work on Monticello 2.1, which will solve  
these problems and lay the groundwork for continued evolution.

Colin



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