I'd like to learn a bit more about the implementation of Weak objects. For example, I see... Magnitude>LookupKey>Associaton >> key: aKey value: anObject key := aKey. value := anObject Magnitude>LookupKey>WeakValueAssociaton >> key: aKey value: anObject key := aKey. self value: anObject Magnitude>LookupKey>WeakValueAssociaton >> value: anObject self at: 1 put: anObject Magnitude>WeakKeyAssociation >> key: aKey value: anObject self basicAt: 1 put: aKey. value := anObject The class definitions don't look any different to normal? I can see that the weak classes are doing an #at:put: for their respective weak attribute, but lots of non-weak classes also use that. So what is it that makes WeakValueAssociaton & WeakKeyAssociation weak ? cheers -ben