Re: [Squeak-VMdev] DING! End of Round One

[Cees de G. <cg...@cd...>]

> Immutability bit
> This sounds intriguing.  Has anyone here thought seriously about what is needed to support it?
> 
Well, as far as you can classify my thinking on this subject as being serious (me being a total nitwit in this area), pseudocode-wise it would be:

Object>>instVarAt: anInteger put: anObject
	self isImmutable ifTrue: [
		AttemptToWriteImmutableObjectException new 
			receiver: self; 
			index: anInteger; 
			value: anObject;
			raise].
	<original code>

Object>>beImmutable: aBoolean
	<primitive...>


that's probably all support you'd need, an extra bit and some code in
#primitiveInstVarAtPut.

I'm using this feature in VisualWorks to support automatic dirty
marking, and it is really nice - it allows you to build very complex
persistent object models that you'd normally avoid because of the dirty
marking hassles.