Non-extensible WeakMaps

Brendan Eich brendan at
Mon Jan 23 12:40:38 PST 2012

> David Bruant <mailto:bruant.d at>
> January 23, 2012 12:37 PM
> Can you elaborate on this last point? Do you mean a run-time way?

No, spec way.

> For the record, this rule (no irrevocable access by default to objects 
> with mutable state) was applied in the design of Joe-E [1], a subset 
> of Java designed to allow object capabilities.

Right, Mark has mentioned that. Indeed it does argue for 
RegExp.prototype being of class Object (no .lastIndex shared mutable).


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