[Newbies] 'locking' an object
bert at freudenbergs.de
Thu Oct 2 17:18:35 UTC 2008
Am 02.10.2008 um 08:50 schrieb Sean Allen:
> If you wanted to take a mutable object and make it immutable and be
> able to go back again to mutable,
> how could you do that?
What is your use case?
> In particular the part that has me as a smalltalk beginner stumped
> is how to disallow any messages
> that would result in a state change while still allowing messages
> that only read state.
> Do you have to handle on a message by message basis? ( Eeek lots and
> lots of work )
> Or is there something you could work into a superclass and use in
> its descendents? ( ideal for what I need. )
Well, it's hardly a beginner's topic, but you could make your class
use a modified compiler that protects instance variable assignment by
the check of an "immutable" flag.
This is basically how Avi's WriteBarrier works.
- Bert -
More information about the Beginners