Btw, if you remember, i already proposed how to solve 'extending object's state with arbitrary state' , mainly by changing the object format to support variable number of key-value properties per object.

Similar to javascript or self, where you can define a new property on a per-object basis.

This is fairly easy to implement, at VM level, just reserve extra field in object format,

define the format of key/value dictionary and add primitives to retrieve and store key-based properties for objects.

What i like in it, that at language side it is cost nothing: you don't have to extend
the language to formally define the slots (but you may, of course),

and there's nothing preventing you from using private keys and not giving them away
to anyone to keep your data private and not exposing it globally (except from reflection tools i guess).

And, what is important, you are free to use them or not.. and it costs almost nothing in terms of performance, and nothing in terms of formalism and extra rules in language/package/source management etc etc

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Best regards,
Igor Stasenko.